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CULTORE DELLA MATERIA presso: Dipartimento di Ingegneria "Enzo Ferrari"

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- Catalyst composition for the preparation of polyesters [Brevetto]
Banach, T. E.; Fiorini, M.; Patel, B. R.; Pilati, Francesco; Berti, C.; Marianucci, E.; Messori, Massimo; C. o. l. o. n. n. a., M.; Toselli, M.

Polyesters are prepd. by the reaction of a dicarboxylic acid, preferably an arom. acid such as terephthalic acid, or an ester or ester-forming deriv. with a dihydroxy compd. such as 1,4-butanediol in the presence of a catalyst compn. comprising the combination of a Ti-based compd. such as tetra-Bu titanate, a Zr-based compd. such as Zr tetrakis(2,4-pentanedionate) and a phosphate-forming compd. such as Na dihydrogen phosphate. This catalyst compn. gives polyesters having relatively low melt viscosities in short reaction times and does not produce an excessive level of undesirable reaction byproducts. Thus, poly(butylene terephthalate) was prepd. from 705 g di-Me terephthalate and 458 g 1,4-butanediol, using tetra-Bu titanate, Zr tetrakis(acetylacetonate), and sodium dihydrogen phosphate at 0.8 mmol Ti and Zr compds./mmol di-Me terephthalate and 245°.

- Catalyst composition for the preparation of polyesters, and related processes [Brevetto]
BANACH T., E; Pilati, Francesco; Colonna, M.; Fiorini, M.; Berti, C.; Toselli, M.; Messori, Massimo; Marianucci, E.

The catalyst compn., an improved method of prepn. of a polyester on the two-stage process of ester interchange and polycondensation, comprises the combination of (a) a titanium-based compd. or zirconium-based compd. and (b) a lanthanide series compd. or hafnium, and optionally, a phosphate-forming compd. Thus, poly(butylene terephthalate) was prepd. by a two-stage polymn. of 1,4-butanediol and di-Me terephthalate in an ester interchange reaction process in the presence of 0.08 phr titanium tetrabutoxide and in a polycondensation stage of 0.14 phr hafnium tetrakis(acetylacetonate).

- Method for preparing poly(cyclohexane-1,4-dicarboxylate)s from cyclohexane-1,4-dicarboxylic acid, and composition [Brevetto]
Dj, Brunelle; C., Berti; Am, Celli; M., Colonna; M., Fiorini; E., Marianucci; Messori, Massimo; Pilati, Francesco; L., Sisti; P., Marchese

Poly(1,4-cyclohexanedicarboxylate)s, esp. poly(1,4-cyclohexanedimethylene-1,4-cyclohexanedicarboxylate), are prepd. from at least one relatively non-volatile diol, such as 1,4-cyclohexanedimethanol, and cyclohexane-1,4-dicarboxylic acid by an esterification process in the presence of a catalyst, at a max. temp. of about 260°. In one embodiment the procedure employs a two-step process, the second of which may be performed in the melt or in the solid state. A volatile diol such as ethylene glycol may also be present. Thus, 1,4-cyclohexanedicarboxylic acid-1,4-cyclohexanedimethanol copolymer with Mw 3,500 and mn 1,400 was prepd. in the presence of tetrakis(2-ethylhexyl) titanate.

- Phosphate-containing catalysts composition for the preparation of polyesters, and related processes [Brevetto]
Banach, T. E.; Fiorini, M.; Patel, B. R.; Pilati, Francesco; Berti, C.; Marianucci, E.; Messori, Massimo; Colonna, M.; Toselli, M.

Polyesters having relatively low melt viscosities and without excessive level of undesirable reaction byproducts in short reaction times are prepd. from a dicarboxylic acid/ester/ester-forming deriv. and a dihydroxy compd. in the presence of a catalyst compn. comprising a Ti-based compd., a Zr-based compd. and a phosphate. Thus, poly(butylene terephthalate) was prepd. from 705 g di-Me terephthalate and 458 g 1,4-butanediol, using tetra-Bu titanate, Zr tetrakis(2,4-pentanedionate), and sodium dihydrogen phosphate at 0.8 mmol Ti and Zr compds. per mmol di-Me terephthalate and 245°.

- Preparation of hydroxy terminated polyarylates [Brevetto]
Brunelle, D. J.; Suriano, J. A.; Berti, C.; Celli, A. M.; Colonna, M.; Fiorini, M.; Marianucci, E.; Marchese, P.; Messori, Massimo; Sisti, L.

Patent WO 2005021616, A1, 20050310, WO 2004-US27424, 20040824

- Two-step process for preparing poly(cyclohexane-1,4-dicarboxylate)s [Brevetto]
D. J., Brunelle; A., Celli; M., Fiorini; C., Berti; M., Colonna; P., Marchese; E., Marianucci; Messori, Massimo; Pilati, Francesco

Poly(1,4-cyclohexanedicarboxylate)s, esp. poly(1,4-cyclohexanedimethylene-1,4-cyclohexanedicarboxylate), are prepd. from 1 relatively nonvolatile diol, such as 1,4-cyclohexanedimethanol, and cyclohexane-1,4-dicarboxylic acid by an esterification process in the presence of a catalyst, at .ltorsim.260°, which is a 2-step process, the second of which may be performed in the melt or in the solid state. A volatile diol such as ethylene glycol may also be present.

2021 - Advantages of Additive Manufacturing for Biomedical Applications of Polyhydroxyalkanoates [Articolo su rivista]
Giubilini, Alberto; Bondioli, Federica; Messori, Massimo; Nyström, Gustav; Siqueira, Gilberto

In recent years, biopolymers have been attracting the attention of researchers and specialists from different fields, including biotechnology, material science, engineering, and medicine. The reason is the possibility of combining sustainability with scientific and technological progress. This is an extremely broad research topic, and a distinction has to be made among different classes and types of biopolymers. Polyhydroxyalkanoate (PHA) is a particular family of polyesters, synthetized by mi- croorganisms under unbalanced growth conditions, making them both bio-based and biodegradable polymers with a thermoplastic behavior. Recently, PHAs were used more intensively in biomedical applications because of their tunable mechanical properties, cytocompatibility, adhesion for cells, and controllable biodegradability. Similarly, the 3D-printing technologies show increasing potential in this particular field of application, due to their advantages in tailor-made design, rapid prototyping, and manufacturing of complex structures. In this review, first, the synthesis and the production of PHAs are described, and different production techniques of medical implants are compared. Then, an overview is given on the most recent and relevant medical applications of PHA for drug delivery, vessel stenting, and tissue engineering. A special focus is reserved for the innovations brought by the introduction of additive manufacturing in this field, as compared to the traditional techniques. All of these advances are expected to have important scientific and commercial applications in the near future.

2021 - Effect of the wine wastes on the thermal stability, mechanical properties, and biodegradation's rate of poly(3-hydroxybutyrate) [Articolo su rivista]
Nanni, A.; Messori, M.

In this work, two different wine derived additives, seeds extracts (Sext) and wine lees (WL), have been tested within poly(3-hydroxybutyrate) (PHB) for different purposes. First, the effect of wine seed polyphenolic extracts (Sext) on the PHB thermal stability has been investigated considering the molecular weight decrease (gel permeation chromatography), the impact on the viscosity (mass flow rate), the thermogravimetric analysis (TGA) curves, and the oxidation induction times. Different stabilizers formulations have been tested and the results have been compared with unstabilized PHB. Subsequently, WL have been mixed in different concentration (10, 20, and 40 phr) within PHB by twin-screw extrusion and the obtained biocomposites have been characterized from a thermal (differential scanning calorimetry and TGA) and mechanical (dynamic mechanical analysis and tensile test) points of view exploiting also the micromechanics models of Voigt, Halpin-Tsai and Pukanszky. Finally, biodegradation tests in soil and in marine water have been carried out for each investigated PHB formulation in order to evaluate the effect of Sext and WL on the microbial degradation.

2021 - Functionalization and use of grape stalks as poly(butylene succinate) (PBS) reinforcing fillers [Articolo su rivista]
Nanni, Alessandro; Cancelli, Umberto; Montevecchi, Giuseppe; Masino, Francesca; Messori, Massimo; Antonelli, Andrea

Grape stalks are a lignocellulosic biomass, which is a very complex material, whose easy and profitable fractionation to obtain its basic components is still not available. Therefore, alternative ways to try and make use of grape stalks are currently being explored. In the present study, the possible use of dried and milled grape stalks as filler in bio-composites was assessed using polybutylene succinate as a basic polymer. The tensile specimens produced using 10% grape stalk powder as it is and functionalized through pre-extrusion acetylation and silylation, and silylation in situ were characterized for their structural, mechanical, thermal, morphological, and color properties. The bio-composites showed to be stiffer than the control polymer, with an increase of Young’s modulus from 616 MPa to 732 MPa in the specimens obtained with acetylated grape stalk powder. This led to a potentially new method to valorize by-products of the wine industry such as grape stalks in order to recover raw materials which could prove useful in the biomaterials and bio-composites sector.

2021 - Protein films from black soldier fly (Hermetia illucens, Diptera: Stratiomyidae) prepupae: effect of protein solubility and mild cross‐linking [Articolo su rivista]
Nuvoli, Daniele; Montevecchi, Giuseppe; Lovato, Francesca; Masino, Francesca; Van Der Borght, Mik; Messori, Massimo; Antonelli, Andrea

BACKGROUND The present work evaluated the performances of protein‐based bioplastics obtained from black soldier fly prepupae (Hermetia illucens). Protein films were synthesized by film casting, both using the whole proteins and their soluble fraction at pH = 10. The effects of glycerol as a plasticizer and of citric acid as a mild cross‐linker onto film properties were also evaluated. RESULTS Films obtained using the soluble protein fraction resulted the strongest, as well as the most homogeneous, and transparent ones. Protein mild cross‐linking improved their tensile properties, especially in films obtained with the whole protein fraction. Non‐cross‐linked samples had a high affinity with water while cross‐linking almost eliminated the ability of films to absorb water. All protein‐based films proved to be an effective barrier to red‐light (T% < 2). CONCLUSION Bioplastics derived from black soldier fly prepupae may find applications in the agricultural sector (biodegradable pots, mulching films, utensils) and deserve to be tested for food and non‐food packaging.

2021 - Valorization of oat hull fiber from agri-food industrial waste as filler for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [Articolo su rivista]
Giubilini, A.; Sciancalepore, C.; Messori, M.; Bondioli, F.

Oat hull fibers are an agri-food industrial waste used in this research as a filler for a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) matrix, to obtain a fully bio-based polymer-matrix composite material. The compounding process was carried out with a twin-screw extruder, avoiding chemical solvents and employing a technology commonly used by the industrial field. Silanization procedure was run to improve the affinity between the matrix and the filler. Compounds were structurally, microstructurally, mechanically and thermally characterized. Results denote that also at 8 v/v%, oat hull fibers work not only as inert filler, but also they have a slightly improving effect on mechanical properties of neat biopolymer, increasing of almost 12% the Young’s modulus, without a loss in tensile elongation at break. Therefore, this research study is a noteworthy approach which reduces the material costs and PHBH volumes, while valorizing waste biomasses.

2020 - 3D-Printing Nanocellulose-Poly(3-hydroxybutyrate- co-3-hydroxyhexanoate) Biodegradable Composites by Fused Deposition Modeling [Articolo su rivista]
Giubilini, A.; Siqueira, G.; Clemens, F. J.; Sciancalepore, C.; Messori, M.; Nystrom, G.; Bondioli, F.

Fabrication of new biobased composites with remarkable properties offers an attractive pathway for producing environmentally friendly materials. Here, a reinforcement for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) with functionalized cellulose nanocrystals (CNCs) is presented and used to successfully 3D-print such composites by fused deposition modeling (FDM). Acetylated CNC content varies from 5 to 20 wt % in order to evaluate the effect of the reinforcing agent on thermal and mechanical properties in the composites. The reinforcing effect of CNC is investigated by dynamic mechanical, thermal, and rheological analysis. Thermogravimetric analysis and infrared spectroscopy allow one to assert the success of chemical functionalization, whereas transmission electron microscopy is used to evaluate the impact of chemical modification on the morphology of the crystals. 3D-printability of biobased composites is proved by developing structures of complex designs with a FDM printer. Finally, the degree of disintegration under composting conditions is studied. Findings from these tests serve as an important step forward toward the development of ecofriendly materials for 3D-printing complex architectures with tailored mechanical properties and functionalities.

2020 - Composizione di resine foto-polimerizzabili, metodo di fabbricazione di un manufatto impiegante la stessa e manufatto cosi’ ottenuto [Brevetto]
Messori, Massimo; Bondioli, Federica; Melli, Giampaolo

2020 - Corrosion resistance of commonly used plumbing materials for water distribution systems exposed to disinfection treatments [Articolo su rivista]

In this study, the corrosion resistance of commonly used plumbing materials was evaluated when three disinfection treatments were applied in hot water distribution systems. In particular copper, brass, stainless steel and galvanised steel were tested in environments containing monochloramine, chlorine dioxide and hydrogen peroxide disinfectants under real field conditions for a long period of time (1 year), in order to evaluate the effect of free corrosion on the metal specimens; chlorinated polyvinylchloride (CPVC) was tested in the same environments in order to evaluate the degradation of the mechanical properties of plastic specimens. The results obtained enabled us to rank the metallic materials corrosion resistance against disinfectants in decreasing order, as follows: stainless steel, copper and copper-based alloys, galvanised steel. CPVC samples proved to be extremely stable in all of the disinfectants investigated, maintaining the same compression behaviour of the pipes aged with untreated water after 12 months of exposure

2020 - Designing epoxy viscosity for optimal mechanical performance of coated Glass Textile Reinforced Mortar (GTRM) composites [Articolo su rivista]
Signorini, C.; Nobili, A.; Sola, A.; Messori, M.

Preliminary epoxy coating of the reinforcing fabric provides an effective approach for improving matrix-to-fabric strength in inorganic matrix composites. We investigate the effect of epoxy resin dilution in acetone on uni-axial tensile performance of coated alkali-resistant (AR) glass fabric embedded in a lime-based matrix. Remarkably, it is found that dilution has a mixed effect on performance and this trend is consistently retrieved for strength, ductility and energy dissipation. Indeed, performance initially decays and then it suddenly raises to a level close to or even exceeding that of the undiluted specimens. It is postulated that this behaviour is caused by resin viscosity, that falls off exponentially with the dilution degree. Once a viscosity threshold is breached, epoxy is capable of penetrating inside the yarn and thereby prevents telescopic failure, that is the sliding of the outer over the inner glass filaments. Furthermore, the interphase surface area increases dramatically and this enhances performance and narrows scattering. Besides, optimal viscosity is reached at an unexpectedly high dilution degree, whence material cost is significantly reduced. A cost-to-performance comparison of common strengthening technologies is presented, which shows that diluted epoxy composites score comparably to FRPs. It is concluded that epoxy coating optimization plays an important role in designing inorganic matrix composites.

2020 - Effect of the wine lees wastes as cost-advantage and natural fillers on the thermal and mechanical properties of poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBH) and poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) [Articolo su rivista]
Nanni, A.; Messori, M.

Solid wine wastes named wine lees (WL) have been tested as cost-advantage filler within biopolymers such as poly(3-hydroxybutyrate-co-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-hydroxyvalerate). WL have been first characterized and subsequently mixed within the polymers through a twin-screw extruder in different concentrations (10, 20, and 40 phr). Moreover, the role of 3-methacryloxypropyltrimethoxysilane tested as coupling agent has been investigated within the 20 phr formulation. The obtained materials have been characterized from a thermal, mechanical, rheological, and morphological point of view through: differential scanning calorimetry, melt flow rate, tensile and creep tests, dynamic mechanical analysis, and scanning electron microscopy. Results have shown how WL can improve the biopolymers overall properties without compromising their bio-based origin. Several micromechanical models have been exploited to extend the mechanical behavior and correlations between biocomposites properties and WL contents have been carried out. Finally, the economic analysis has shown how these biocomposites could be suitable also for large-scale applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48869.

2020 - Influence of atmospheric pressure plasma process parameters on the mechanical behavior of thermoplastic joints [Articolo su rivista]
Moroni, F.; Musiari, F.; Sciancalepore, C.; Messori, M.

The capability of the Atmospheric Pressure Plasma Treatment (APPT) to increase the shear strength of adhesively bonded Single Lap Joints (SLJ) realized with polymeric adherends was investigated, by exploring the different response obtainable by changing the surface-to-nozzle distance and the treatment speed and by considering an industrial application as target. Beyond APPT, abrasion and chemical treatments were also performed and considered as reference. Three thermoplastic resins were used as adherends: polypropylene (PP), polyethylene (PE) and polyamide 66 (PA66). In addition to the mechanical characterization, even the variation of the surface free energy associated with the different combinations of parameters employed for the APPT was evaluated by means of optical contact angle (OCA) measurements. Moreover, for some representative combinations of substrates and APPT parameters, the changes of the polymer chemical structure were assessed by means of infra-red spectroscopy (IR). Finally, the sensitivity of the mechanical behavior to the time between the treatment and the deposition of the adhesive was assessed. The results showed that, in a plasma treated joint, a decrease of the surface-to-nozzle distance assured however an increase of the shear strength with respect to the chemical treated samples, provided that the treatment speed was correspondingly risen up. The trend of the wettability with the process configuration appeared to be consistent with the one exhibited by the joint shear strength, while any apparent influence of the delay time was detectable within 24 h, which allowed to assume that APPT represents a reliable pre-treatment technique for industrial applications.

2020 - New biocomposite obtained using poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and microfibrillated cellulose [Articolo su rivista]
Giubilini, A.; Sciancalepore, C.; Messori, M.; Bondioli, F.

This research evaluates the effects of filler content and silanization on thermal, morphological and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based composites. Microfibrillated cellulose (MFC) was obtained by a mechanical treatment of high-pressure homogenization, starting from oat hull fiber, a byproduct of the agri-food sector. MFC reinforced PHBH composites were prepared by melt compounding. SEM and FT-IR analysis showed a good dispersion of the filler in the polymeric matrix, denoting the effectiveness of the surface silanization process. The thermal stability of PHBH composites remains substantially unchanged, and the glass transition temperature marginally increases with the increase of the filler content. Furthermore, silanized MFC shows slightly reinforcing mechanical effects on PHBH composites, such as the increase of 10% of the Young modulus with an increase of the maximum tensile stress as well. This finding has an economical interest since the results showed that MFC, deriving from a byproduct, can be successfully used as filler, decreasing the cost of the bio-based compound leaving substantially unaltered its mechanical and thermal properties. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48953.

2020 - Optimal epoxy dilution for epoxy-coated textile reinforced mortar (Trm): An experimental perspective [Relazione in Atti di Convegno]
Signorini, C.; Nobili, A.; Sola, A.; Messori, M.

The effect of epoxy dilution with acetone on the mechanical performance of epoxy-coated alkali-resistant glass (ARG) fabric embedded in a lime-based mortar is studied experimentally. The mechanical behaviour of the composite system is assessed in uni-axial tensile tests, according to the ICC guidelines. Epoxy is diluted in acetone and several concentrations, namely 10%, 25%, 50%, 75% and 90%, are considered in an attempt to define a decay law for strength, ductility and dissipated energy at failure. Although epoxy-coating promotes a striking improvement of the mechanical performance with respect to the uncoated specimens, epoxy dilution appears to little affect the global response, even at very low epoxy-to-solvent ratios. Actually, a notable increase in the ultimate strength and strain as well as dissipation capacity are evidenced for 75% dilution. Indeed, epoxy resin is able to uniformly impregnate the bundles of the yarns in a very thin layer, still preserving its contribution to the mechanical performance. In fact, wettability of the yarns plays a fundamental role in the mechanical performance of the laminate for it limitates telescopic failure. A threshold of viscosity is identified. Above this limit, the high quality of impregnation overcomes the issue of the reduction of the amount of epoxy resin in the coating. Besides, dilution strongly promotes the ease of application, as a result of the resin viscosity being sharply reduced. Most remarkably and contrarily to common expectation, the specific energy dissipated at failure exhibits a maximum point, whence an optimal dilution ratio exists which best balances interphase strength and ductility.

2020 - Thermo-mechanical properties and creep modelling of wine lees filled Polyamide 11 (PA11) and Polybutylene succinate (PBS) bio-composites [Articolo su rivista]
Nanni, A.; Messori, M.

Solid wine wastes named wine lees (WL) have been mixed in different percentages (10, 20 and 40 phr) within Polyamide 11 (PA11) and Polybutylene Succinate (PBS) by twin-screw extrusion. Reactive extrusion has been also tested using 3-methacryloxypropyltrimethoxysilane tested as coupling agent. The obtained bio-composites have been characterized from a thermal (DSC, TGA, HDT), rheological (MFR), mechanical (tensile test) and thermo-mechanical (DMA, creep test) point of view. Micro-mechanics models of Voigt, Halpin-Tsai and Pukanszky have been fitted on tensile properties data meanwhile the creep behavior has been modeled and described through the models of Burger, Kohlrausch-Williams-Watts and Findley.

2020 - Thermoplastic disks used for commercial orthodontic aligners: Complete physicochemical and mechanical characterization [Articolo su rivista]
Daniele, V.; Macera, L.; Taglieri, G.; Di Giambattista, A.; Spagnoli, G.; Massaria, A.; Messori, M.; Quagliarini, E.; Chiappini, G.; Campanella, V.; Mummolo, S.; Marchetti, E.; Marzo, G.; Quinzi, V.

Invisible orthodontic aligners (IOAs) have been introduced in the orthodontic field as an innovative alternative for fixed brackets, in relation to their ability to be easily inserted/removed from the oral cavity without affecting the chewing ability and the aesthetic of the patients. The paper provides a complete physicochemical and mechanical characterization of thermoplastic materials in the form of disks used for commercial IOAs. A wide palette of specific techniques is considered, from tensile tests and dynamic-mechanical analysis, to X-Ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transformation infrared spectroscopy (FTIR-ATR) analyses and water absorption tests. The disks are investigated before and after immersion into staining beverages (red wine, coffee, nicotine and artificial saliva), in terms of colour variations, transparency, and microscopic surface modifications by means of colorimetry, UV-VIS absorbance and scanning electron microscopy (SEM). Among all the samples, polyurethane (PU) exhibited the highest crystallinity and the highest values of mechanical and thermal resistance, while the poly(ethylene terephthalate)-glycol (PETG) samples presented better transparency and less ability to absorb water. Moreover, red wine and coffee give noticeable colour variations after 14 days of immersion, together with a slight reduction of transparency.

2020 - Wine derived additives as poly(butylene succinate) (PBS) natural stabilizers for different degradative environments [Articolo su rivista]
Nanni, A.; Ricci, A.; Versari, A.; Messori, M.

A grape pomace extract (GPext) and a grape seed extract (T) have been melt mixed within poly(butylene succinate) (PBS) and tested as natural stabilizers. Their effect on the PBS stabilization has been evaluated trough thermo-mechanical degradative tests (reprocessing), thermo-oxidation (oven aging), thermogravimetric analysis (TGA) and biodegradation tests. GPext and T have been deeply analyzed in terms of polyphenolic profile and bioactivity to connect the stabilization's results with the antioxidant's structures. Additive T exhibited the best results, maintaining unaltered the PBS molecular weight both after six reprocessing steps and after 300 h of oven aging and to increase the degradation temperature of more than 20 °C. These encouraging results have been explained by the long-chains polyphenols present within T (medium degree of polymerization of 10.8), by the excellent radical scavenger activity of T (6.0 mM TEAC) and by the low releases of peroxides from T (0.06 µM H2O2).

2019 - Design and Characterization of Novel Potentially Biodegradable Triple-Shape Memory Polymers Based on Immiscible Poly(l-lactide)/Poly(ɛ-caprolactone) Blends [Articolo su rivista]
Molavi, Fatemeh Khademeh; Ghasemi, Ismaeil; Messori, Massimo; Esfandeh, Masoud

In this study, covalently cross-linked network strategy has been applied to prepare new triple-shape memory polymers (TSPs) based on poly(l-lactide) (PLA)/poly(ɛ-caprolactone) (PCL) blends. The TSPs were fabricated by adding di-cumyl peroxide, with triallyl isocyanurate as a coagent for performing the cross-linking reaction. The differential scanning calorimetry (DSC) analysis demonstrated that all the PLA/PCL blends show two melting points (T m,PCL and T m,PLA ), which can be employed as the transition temperature (T trans ) to induce triple-shape memory behavior. The scanning electron microscopy (SEM) analysis indicated that there are two immiscible morphologies: co-continuous structure and matrix-droplet. The influence of temperature on the crystalline phase changes was analyzed by X-ray diffraction at various temperatures. The results revealed that during the heating–cooling cycle, the degree of crystallinity decreased when the temperature increased and at higher temperature, the crystallization peaks of PCL disappeared. Multiple thermal–mechanical tests were performed and the results showed that the composition ratio of the two phases plays an important role in the triple-shape memory behavior. The results confirmed that the excellent shape memory behavior was obtained for the sample containing 50 wt% PCL.

2019 - Development of solvent-casting particulate leaching (SCPL) polymer scaffolds as improved three-dimensional supports to mimic the bone marrow niche [Articolo su rivista]
Sola, Antonella; Bertacchini, Jessika; D'Avella, Daniele; Anselmi, Laura; Maraldi, Tullia; Marmiroli, Sandra; Messori, Massimo

The need for new approaches to investigate ex vivo the causes and effects of tumor and to achieve improved cancer treatments and medical therapies is particularly urgent for malignant pathologies such as lymphomas and leukemias, whose tissue initiator cells interact with the stroma creating a three-dimensional (3D) protective environment that conventional mono- and bi-dimensional (2D) models are not able to simulate realistically. The solvent-casting particulate leaching (SCPL) technique, that is already a standard method to produce polymer-based scaffolds for bone tissue repair, is proposed here to fabricate innovative 3D porous structures to mimic the bone marrow niche in vitro. Two different polymers, namely a rigid polymethyl methacrylate (PMMA) and a flexible polyurethane (PU), were evaluated to the purpose, whereas NaCl, in the form of common salt table, resulted to be an efficient porogen. The adoption of an appropriate polymer-to-salt ratio, experimentally defined as 1:4 for both PMMA and PU, gave place to a rich and interconnected porosity, ranging between 82.1 vol% and 91.3 vol%, and the choice of admixing fine-grained or coarse-grained salt powders allowed to control the final pore size. The mechanical properties under compression load were affected both by the polymer matrix and by the scaffold's architecture, with values of the elastic modulus indicatively varying between 29 kPa and 1283 kPa. Preliminary tests performed with human stromal HS-5 cells co-cultured with leukemic cells allowed us to conclude that stromal cells grown associated to the supports keep their well-known protective and pro-survival effect on cancer cells, indicating that these devices can be very useful to mimic the bone marrow microenvironment and therefore to assess the efficacy of novel therapies in pre-clinical studies.

2019 - Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11 [Articolo su rivista]
Oulmou, F.; Benhamida, A.; Dorigato, A.; Sola, A.; Messori, M.; Pegoretti, A.

The preparation and thermo-mechanical characterization of composites based on polyamide 11 (PA11) filled with various amounts of both expandable and expanded graphites are presented. Investigation conducted using X-ray diffraction (XRD), scanning electron microscopy and surface area analyses indicated how graphite expanded under the selected processing conditions. The XRD analysis on PA11/graphite composites revealed no change in the crystal form of the PA11, while the presence of diffraction peaks associated to the graphite-stacked lamellae can be still detected. All the investigated composites showed an improvement of the thermal stability and mechanical properties (elastic and storage moduli).

2019 - Effect of high temperature exposure on epoxy-coated glass textile reinforced mortar (GTRM) composites [Articolo su rivista]
Messori, M.; Nobili, A.; Signorini, C.; Sola, A.

An experimental investigation on the mechanical performance of epoxy-coated Alkali-Resistant (AR) glass textile reinforced mortar subjected to elevated temperature is presented. Two epoxy coatings are considered, which differ by the hardening agent alone. After 56 days dry curing, specimens are heated up to four different temperatures. After cooling down to ambient temperature, specimens are assessed in uni-axial tensile test according to Annex A of AC434. First cracking strength and elongation, ultimate tensile strength and elongation, cracked and uncracked moduli, transition point location and energy dissipation capability are evaluated. It is found that, in the explored temperature range, degradation is surprisingly mild and strongly dependent on the resin which is taken as coating agent. Indeed, temperature exposure may lead to strength enhancement. This positive outcome takes place at the expense of ductility and it is traced back, through Differential Scanning Calorimetry (DSC), to a post-curing process. Nonetheless, energy dissipation still decreases with temperature and, remarkably, with the same power-law behaviour for both resins. Such behaviour is compatible with a cumulative Weibull distribution, that is adopted in thermal damage models for resins, and it indicates that the underlying damage mechanism indeed operates on the resin at the fabric-to-matrix interface. (C) 2019 Elsevier Ltd. All rights reserved.

2019 - Materiale composito formato da un biofiller e da una matrice termoplastica e procedimento per realizzare un articolo con un tale materiale composito [Brevetto]
Nanni, Alessandro; Messori, Massimo

2019 - Rational design and characterization of bioplastics from Hermetia illucens prepupae proteins [Articolo su rivista]
Barbi, Silvia; Messori, Massimo; Manfredini, Tiziano; Pini, Martina; Montorsi, Monia

In this study proteins extracted from prepupae of Hermetia illucens, also known as black soldier fly,are investigated as promising base for a new type of bioplastics for agricultural purposes. Designof experiments techniques are employed to perform a rational study on the effects of differentcombination of glycerol as plasticizer, citric acid as cross-linking agent and distilled water as solventon the capability of proteins to form a free-standing film through casting technique, keeping asfixed the quantity of proteins. Glycerol shows interesting properties as plasticizer contributing tothe formation of homogenous and free-standing film. Moreover, mechanical and thermalcharacterizations are performed to estimate the effect of increasing amounts of proteins on thefinal properties and thickness of the specimens. Proteins derived from H. illucens can be success-fully employed as base for bioplastics to be employed for agricultural purposes.

2019 - Structure and properties of polyamide 11 nanocomposites filled with fibrous palygorskite clay [Articolo su rivista]
Benobeidallah, B.; Benhamida, A.; Dorigato, A.; Sola, A.; Messori, M.; Pegoretti, A.

Various amounts (up to 10 wt%) of palygorskite nanofibers functionalized by 3-aminopropyltriethoxysilane (APTES) coupling agent were used to reinforce polyamide 11 nanocomposites prepared by melt compounding. The covalent bonding of the silane on the palygorskite surface was confirmed by infrared spectroscopy and thermogravimetric analysis. X-ray diffraction revealed the retention of the α-form of polyamide crystals upon the addition of both natural and silane treated palygorskite nanorods. All the investigated nanocomposites showed an improvement of the thermal stability, especially when surface treated palygorskite nanofibers were considered. Tensile tests and dynamic mechanical thermal analyses on the prepared materials evidenced how the incorporation of palygorskite nanofibers significantly increased the elastic and the storage moduli of polyamide, and this enhancement was more evident when natural palygorskite nanorods were used.

2019 - Synthesis and Characterization of Semiconductor Polymer Doped with FeCl3 and I2 [Articolo su rivista]
Bouabdallah, Daho; Fontanesi, C.; Messori, M.; Dehbi, A.; Belfedal, A.

Abstract: The conductive polymer-based applications combine low cost, simple manufacturing procedure, flexibility and other properties. However, the low viscosity and solubility of these polymers make it difficult to produce layers by using industrial techniques. Among the most commonly used conjugated conductive organic polymers we can mention polyacetylene, polythiophene, polypyrrole, polyaniline, etc. In order to test them in further applications, new copolymers of thiophene and p-methoxybenzaldehyde were synthesized. The copolymers obtained will be characterized by several techniques (NMR, UV, CV, ATG, and electrical characterization). The study of the optical properties after doping is performed according to oxidation-reduction reactions by FeCl3, I2, in order to apprehend the redox behavior of this copolymer. The calculated value of energy gap Egcv of the studied polymers shows a decrease with the oxidation agent doping according to their oxidation potential, from 2.48 eV for the no doped copolymer passing by 2.22 eV for the copolymer doped with I2 and up to 1.5 eV for the copolymer doped with FeCl3. The decrease of the energy gap with the doping (FeCl3 and I2) corresponds to the increase of the conductivity with doping from 2.85 × 10–5 S m–1 for no doped polymer to 7.86 × 10–5 S m–1 for copolymer doped with I2 and 1.55 × 10–4 S m–1 for copolymer doped with FeCl3.

2019 - Thermal and UV aging of polypropylene stabilized by wine seeds wastes and their extracts [Articolo su rivista]
Nanni, A.; Battegazzore, D.; Frache, A.; Messori, M.

A commercial tannin wine seed extract powder (T), a seed polyphenol extract (Sext) and virgin wine seeds wastes (Se) have been mixed with polypropylene (PP) and tested as long-term stabilizers. Their stabilizing activity has been compared with that of a synthetic antioxidant commonly used within PP (Irganox 1010). Each sample has been subject to both UV and thermal aging. The PP-based films photo-oxidation has been followed through the C=O formation over the aging time by FT-IR. The PP-based tensile specimens have been oven aged and the mechanical properties loss has been investigated monitoring the variation of the elongation at break. Melt Flow Index (MFI) measures and Different Scanning Calorimetry analysis have been conducted on thermally aged samples. At the same time, wine derived additives have been characterized in terms of total polyphenol content, FT-IR and UV/VIS spectra meanwhile catechin and gallic acid have been quantified by LC-MS. Experimental results have evidenced the ability of all the wine derived additives to withstand both to thermal and UV long-term degradation. In particular, wine seeds extracts exhibit the best results in terms of stabilization (even better than Irganox 1010) without compromising the PP mechanical, thermal, morphological and rheological properties.

2019 - Verwey transition temperature distribution in magnetic nanocomposites containing polydisperse magnetite nanoparticles [Articolo su rivista]
Barrera, G.; Tiberto, P.; Sciancalepore, C.; Messori, M.; Bondioli, F.; Allia, P.

Polymeric nanocomposites containing Fe 3 O 4 nanoparticles were prepared through a chemical route under different precursor-to-solvent ratios and were submitted to structural and morphologic characterization. The embedded nanoparticles, containing pure magnetite and characterized by considerable polydispersity, are rather homogeneously dispersed in the matrix. The magnetic properties of two representative samples were analyzed in detail between T = 5 K and room temperature. Magnetic effects clearly associated with the Verwey monoclinic to cubic transition with transition temperatures distributed in the interval 95–120 K were put in evidence. On heating through this region, the coercive field and the maximum susceptibility of hysteresis loops display marked downward/upward steps, respectively, while the high-field magnetization is not affected at all; a comparable upward step is measured in the FC/ZFC curves. Reporting the maximum susceptibility as a function of the reciprocal of the coercive field in the interval from T = 95 to T = 120 K, and using the predictions for single-domain nanoparticles with randomly distributed axes of uniaxial and cubic anisotropy (the former/latter case being applicable below/above the Verwey transition, respectively), the evolution of the transformed cubic-anisotropy fraction upon heating has been studied, and the distribution of Verwey transition temperatures related to the sample polydispersity has been accurately determined. The low-temperature value of the uniaxial anisotropy constant is obtained from coercive field measurements and found to be comparable to, albeit slightly higher than the corresponding quantity measured in bulk crystalline magnetite.

2018 - 3D printing processes for photocurable polymeric materials: technologies, materials, and future trends [Articolo su rivista]
Taormina, Gabriele; Sciancalepore, Corrado; Messori, Massimo; Bondioli, Federica

The aim of this review is a faithful report of the panorama of solutions adopted to fabricate a component using vat photopolymerization (VP) processes. A general overview on additive manufacturing and on the different technologies available for polymers is given. A comparison between stereolithography and digital light processing is also presented, with attention to different aspects and to the advantages and limitations of both technologies. Afterward, a quick overview of the process parameters is given, with an emphasis on the necessities and the issues associated with the VP process. The materials are then explored, starting from base matrix materials to composites and nanocomposites, with attention to examples of applications and explanations of the main factors involved.

2018 - A comparative study of different winemaking by-products derived additives on oxidation stability, mechanical and thermal proprieties of polypropylene [Articolo su rivista]
Nanni, A.; Messori, M.

Three different solid wine wastes (peels, seeds and stalks) have been mixed with polypropylene (PP) and tested as stabilizers. Their stabilizing activity has been compared with that of a commercial tannin extract powder, rich in polyphenol. Thermogravimetric analysis, Oxidation Induction Time and Oxidation Onset Temperature measurements have been conducted to investigate the thermo-oxidative stability. Tensile tests, Dynamic Mechanical Analysis and Differential Scanning Calorimetry have been conducted on the samples in order to evaluate the effect of the additives also on the thermal and mechanical properties. Scanning Electron Microscopy have been used to assess the adhesion and distribution of the wine-wastes additives within the PP matrix. Experimental results evidence that all three wine-wastes derived additives do not significantly change the mechanical and thermal properties of PP, meanwhile they enhance its thermal stability. Moreover, the expectation to obtain better results with the commercial tannin extract has not been achieved. The obtained results show how wine wastes can be effectively used as polymer stabilizers and represent a valid alternative because of theirs environmental and cost-effects advantages.

2018 - A one-dimensional phenomenological model for the two-way shape-memory effect in semi-crystalline networks [Articolo su rivista]
Scalet, Giulia; Pandini, Stefano; Messori, Massimo; Toselli, Maurizio; Auricchio, Ferdinando

The shape-memory effect (SME) in polymers is a stimuli-responsive feature that is attracting more and more attention, thanks to its usage in fields ranging from the biomedical sector to soft robotics. The two-way SME, in particular, has great potential for applications needing repeated cycling, e.g., actuators, and motivates the development of theoretical and numerical tools to support their design. The present paper aims to propose a one-dimensional finite-strain phenomenological model to describe the one-way SME as well as the two-way SME under stress conditions in thermo-responsive semi-crystalline crosslinked polymers. The model is simple, easy to implement, and based on parameters with a clear and direct physical interpretation and measurability. Model predictions are validated on experiments on semi-crystalline networks based on poly(ε-caprolactone) and demonstrate model ability in describing several material features as the effect of the crosslink density on SME, the dependence of microstructural evolution on applied load and heating/cooling rate, and the presence of thermal strains.

2018 - Advanced resins for stereolithography: In situ generation of silver nanoparticles [Relazione in Atti di Convegno]
Taormina, G.; Sciancalpore, C.; Messori, M.; Bondioli, F.

The present study demonstrates the feasibility of stereolithographic 3D printing of composite objects based on acrylic photocurable formulations, containing in situ generated silver nanoparticles (AgNPs). The laser radiation of a commercial stereolithography printer was used to both selectively cure, layer by layer, the acrylic resin and to reduce a silver salt to AgNPs. The presence of the filler causes an increase in the physical and mechanical properties of the samples that become significantly stiffer and stronger than the pristine matrix.

2018 - Angiogenic and inflammatory potential of Scleral Ossicles, novel natural biomaterials for bone regeneration [Abstract in Rivista]
Checchi, Marta; Bertacchini, Jessika; Magaro', MARIA SARA; Ferretti, Marzia; Sola, Antonella; Bisi, Francesca; Messori, Massimo; Ribatti, Domenico; Maurel, Delphine; Palumbo, Carla

The aim of this work is the analysis of the angiogenic and inflammatory potential of the Scleral Ossicles (SOs), already analysed by the structural viewpoint, and the development of a functionalized-SOs-construct. The final goal is to improve the healing of critical-size bone fractures.

2018 - Carbon on poly(epsilon-caprolactone) (PCL) ink-jet printed sensor for monitoring cell cultures of myoblasts [Relazione in Atti di Convegno]
Marziano, M.; Tonello, S.; Serzanti, M.; Borghetti, M.; Lopomo, N. F.; Serpelloni, M.; Pandini, S.; Merlettini, A.; Gualandi, C.; Focarete, M. L.; Messori, M.; Toselli, M.; Uberti, D.; Memo, M.; Dell’Era, P.; Sardini, E.

Nowadays techniques for sensitive non-invasive, real-time monitoring of cell differentiation and maturation are highly demanded. In light of this, the development of electrochemical printed sensors impedance-based could represent a promising tool. In the present work, we developed 2D ink-jet printed sensors for myoblasts adhesion monitoring, using carbon-based ink on a substrate consisting in non-woven electrospun mats made in crosslinked poly(ε-caprolactone) (PCL). First of all, sensors printability was optimized and the biocompatibility tested. In order to determine the possibility to employ the prepared systems as scaffolds for dynamic cellular cultures, the mechanical response of the PCL scaffold was evaluated through the application of cyclic deformation tests. After that, electrical characterization of ink and substrate was performed, followed by electrochemical impedance-based measurements to evaluate myoblasts adhesion. Biocompatibility assessment showed good results for both carbon and PCL. Mechanical tests findings suggested that a training of 50 cycles and a proper value of strain should be applied before the cell seeding, in order to ensure a subsequent controlled strain amplitude. The sensorized scaffold allowed us to correlate cell adhesion with an increase of impedance module, in agreement with biocompatibility testing. Thus, this first preliminary testing suggested that this non-invasive impedance spectroscopy-based measurement system can be used for sensitive monitoring of cells adhesion, in static and moreover, as suggested from mechanical characterization, in dynamic conditions.

Messori, Massimo; Bondioli, Federica; Taormina, Gabriele; Sciancalepore, Corrado

2018 - Mechanical performance of epoxy coated AR-glass fabric Textile Reinforced Mortar: Influence of coating thickness and formulation [Articolo su rivista]
Messori, Massimo; Nobili, Andrea; Signorini, Cesare; Sola, Antonella

The mechanical performance of epoxy coated AR-glass fabric reinforced composite is investigated. A three-stage manufacturing process is considered, which involves fabric surface functionalization, liquid coating deposition and long-term setting and finally fabric embedment in the mortar matrix. Two epoxy coatings are considered, which only differ by the hardening agent. However, coating thickness is significantly diverse as a result of modified viscosity during liquid deposition. Performance is assessed in uni-axial tension as well as in three-point bending and it is expressed in terms of strength curves, data dispersion, crack pattern and failure mechanism. Remarkably, despite being very similar, the analyzed coatings produce a significantly different performance, especially when data dispersion is incorporated and design limits are considered. Indeed, although both coatings are able to consistently deliver fabric rupture at failure, only the thinnest is associated with small data scattering and an almost plastic post-peak behavior in bending. The associated design elongation limit reaches the maximum allowed value according to the ICC guidelines. In fact, it appears that coating thickness plays a crucial role in determining mechanical performance and fabric flexibility. The proposed manufacturing process proves extremely effective at enhancing matrix-to-fabric adhesion and thereby prevent telescopic failure.

2018 - Proposal of a Novel Natural Biomaterial, the Scleral Ossicle, for the Development of Vascularized Bone Tissue In Vitro [Articolo su rivista]
Checchi, Marta; Bertacchini, Jessika; Grisendi, Giulia; Smargiassi, Alberto; Sola, Antonella; Messori, Massimo; Palumbo, Carla

Recovering of significant skeletal defects could be partially abortive due to the perturbations that affect the regenerative process when defects reach a critical size, thus resulting in a non-healed bone. The current standard treatments include allografting, autografting, and other bone implant techniques. However, although they are commonly used in orthopedic surgery, these treatments have some limitations concerning their costs and their side effects such as potential infections or malunions. On this account, the need for suitable constructs to fill the gap in wide fractures is still urgent. As an innovative solution, scleral ossicles (SOs) can be put forward as natural scaffolds for bone repair. SOs are peculiar bony plates forming a ring at the scleral-corneal border of the eyeball of lower vertebrates. In the preliminary phases of the study, these ossicles were structurally and functionally characterized. The morphological characterization was performed by SEM analysis, MicroCT analysis and optical profilometry. Then, UV sterilization was carried out to obtain a clean support, without neither contaminations nor modifications of the bone architecture. Subsequently, the SO biocompatibility was tested in culture with different cell lines, focusing the attention to the differentiation capability of endothelial and osteoblastic cells on the SO surface. The results obtained by the above mentioned analysis strongly suggest that SOs can be used as bio-scaffolds for functionalization processes, useful in regenerative medicine.

2018 - Rubber-filler interactions in polyisoprene filled with in situ generated silica: A solid state NMR study [Articolo su rivista]
Borsacchi, Silvia; Sudhakaran, Umayal Priyadharsini; Calucci, Lucia; Martini, Francesca; Carignani, Elisa; Messori, Massimo; Geppi, Marco

In this paper we used high- and low-resolution solid state Nuclear Magnetic Resonance (NMR) techniques to investigate a series of polyisoprene samples filled with silica generated in situ from tetraethoxysilane by sol-gel process. In particular, 1 H spin-lattice and spin-spin relaxation times allowed us to get insights into the dynamic properties of both the polymer bulk and the bound rubber, and to obtain a comparative estimate of the amount of bound rubber in samples prepared with different compositions and sol-gel reaction times. In all samples, three fractions with different mobility could be distinguished by 1 H T 2 and ascribed to loosely bound rubber, polymer bulk, and free chain ends. The amount of bound rubber was found to be dependent on sample preparation, and it resulted maximum in the sample showing the best dispersion of silica domains in the rubber matrix. The interpretation of the loosely bound rubber in terms of "glassy" behaviour was discussed, also on the basis of 1 H T 1 and T 1ρ data.

2018 - Special Resins for Stereolithography: In Situ Generation of Silver Nanoparticles [Articolo su rivista]
Taormina, Gabriele; Sciancalepore, Corrado; Bondioli, Federica; Messori, Massimo

The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA) or digital light processing (DLP) due to a strong increment of viscosity derived from the presence of rigid particles within the reactive suspension. In the present paper, the possibility to in situ generate silver nanoparticles (AgNPs) starting from a homogeneous liquid system containing a well dispersed silver salt, which is subsequently reduced to metallic silver during stereolithographic process, is reported. The simultaneous photo-induced cross-linking of the acrylic resin produces a filled thermoset resin with thermal-mechanical properties significantly enhanced with respect to the unfilled resin, even at very low AgNPs concentrations. With this approach, the use of silver salts having carbon-carbon double bonds, such as silver acrylate and silver methacrylate, allows the formation of a nanocomposite structure in which the release of by-products is minimized due to the active role of all the reactive components in the three dimensional (3D)-printing processes. The synergy, between this nano-technology and the geometrical freedom offered by SLA, could open up a wide spectrum of potential applications for such a material, for example in the field of food packaging and medical and healthcare sectors, considering the well-known antimicrobial effects of silver nanoparticles.

2018 - Structural characterization and functional correlation of Fe3O4 nanocrystals obtained using 2-ethyl-1,3-hexanediol as innovative reactive solvent in non-hydrolytic sol-gel synthesis [Articolo su rivista]
Sciancalepore, C.; Gualtieri, A. F.; Scardi, P.; Vivas De Gonzalez, Flor Alba; Allia, P.; Tiberto, P.; Barrera, Giulia; Messori, M.; Bondoli, F.

An original non-hydrolytic sol-gel approach, using 2-ethyl-1,3-hexanediol as reactive solvent, was proposed to synthetize nanostructured magnetite. Iron-oxide nanoparticles were prepared and studied as a function of the precursor-to-solvent ratio. The crystallization degree of nanoparticles was followed by the combined Rietveld and Reference Intensity Ratio method. This procedure has allowed the determination of both amorphous and crystalline content of nanomagnetite, using hematite as suitable internal standard. The results of Rietveld method show that the crystalline content decreases as the precursor-to-solvent is increased, ranging from 67 to 60 wt%. Information on the crystallite size-strain distribution and microstructural evolution of nanocrystals was supplied by line profile analysis of the powder diffraction patterns, employing the Whole Powder Pattern Modeling analysis: the obtained log-normal distribution curves become increasingly narrow and symmetrical, while nanoparticle microstrain increases as the precursor concentration is increased. The dimensional analysis of the Transmission Electron Microscopy images has allowed to obtain the nanoparticle grain-size distribution. Nanoparticle dimensions decreases from 15 to 9 nm increasing the precursor concentration. The comparison between the results of X-ray diffraction and microscopic characterization techniques highlighted the effect of several factors, such as size, shape and microstructure of magnetite nanoparticles, on their functional magnetic response. Magnetic characterizations show that magnetite nanoparticles are not in the superparamagnetic phase even at room temperature, independent of the precursor concentration. On the other hand, the room-temperature saturation magnetization, ranging from 73 to 60 emu/g, is a function of the nanoparticle average size, decreasing as the precursor concentration increases.

2017 - Acrylate-based silver nanocomposite by simultaneous polymerization-reduction approach via 3D stereolithography [Articolo su rivista]
Sciancalepore, Corrado; Moroni, Fabrizio; Messori, Massimo; Bondioli, Federica

This study demonstrates the feasibility of printing 3D composite objects based on acrylic photocurable formulations, containing in situ generated silver nanoparticles (AgNPs). In fact, the laser radiation of a commercial stereolithography printer was used to both selectively cure, layer by layer, the acrylic resin and to reduce a silver salt to AgNPs (having dimensions ranging between 10 and 25 nm). The most suitable formulation was developed using silver acetate to obtain 1% by weight of AgNPs in the final 3D structures. The presence of the filler causes an increase in the physical and mechanical properties of the samples that become significantly stiffer and stronger than the pristine matrix. Antibacterial properties and electrical conductivity measurements performed on the printed samples gave promising results for the use of the developed formulation for the building of 3D polymeric structures with improved multifunctional properties.

2017 - Increased production of bacterial cellulose as starting point for scaled-up applications [Articolo su rivista]
Gullo, Maria; Sola, Antonella; Zanichelli, Gabriele; Montorsi, Monia; Messori, Massimo; Giudici, Paolo

Bacterial cellulose is composed of an ultrafine nanofiber network and well-ordered structure; therefore, it offers several advantages when used as native polymer or in composite systems. In this study, a pool of 34 acetic acid bacteria strains belonging to Komagataeibacter xylinus were screened for their ability to produce bacterial cellulose. Bacterial cellulose layers of different thickness were observed for all the culture strains. A high-producing strain, which secreted more than 23 g/L of bacterial cellulose on the isolation broth during 10 days of static cultivation, was selected and tested in optimized culture conditions. In static conditions, the increase of cellulose yield and the reduction of by-products such as gluconic acid were observed. Dried bacterial cellulose obtained in the optimized broth was characterized to determine its microstructural, thermal, and mechanical properties. All the findings of this study support the use of bacterial cellulose produced by the selected strain for biomedical and food applications.

2017 - Magnetite-epoxy nanocomposites obtained by the reactive suspension method: Microstructural, thermo-mechanical and magnetic properties [Articolo su rivista]
Barrera, G.; Sciancalepore, C.; Messori, M.; Allia, P.; Tiberto, P.; Bondioli, F.

Magnetite nanoparticles are prepared by non-hydrolytic sol-gel process in the presence of iron(III)-acetylacetonate as precursor and 2-ethyl-1,3-hexanediol as reactive solvent; the nanoparticle size is affected by the precursor-to-solvent ratio. The suspensions, mixed with bisphenol-A diglycidyl ether, are cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. The chain-growth polymerization results in a three-dimensional network where the diol, acting at the same time as reactive solvent and suspending medium, is covalently linked to the epoxy network according to the “activated monomer” mechanism. The filler induces stiffening because of hydrodynamic effects and of a better cross-linking ability in the nanocomposite. Magnetite nanoparticles form aggregates whose size and shape depend on concentration. Isothermal magnetization loops and FC/ZFC DC susceptibility curves indicate that all nanocomposites are dominated by interparticle magnetic interactions resulting in a collective response whose details depend on nanoparticle concentration and degree of aggregation.

2017 - Mutifunctional Electrospun Nonwoven Mats with Two-Way Shape Memory Behavior Prepared from Sol-Gel Crosslinked Poly(epsilon-Caprolactone) [Articolo su rivista]
Pandini, Stefano; Agnelli, Silvia; Merlettini, Andrea; Chiellini, Federica; Gualandi, Chiara; Paderni, Katia; Focarete, Maria Letizia; Messori, Massimo; Toselli, Maurizio

Nonwoven fibrous mats based on semicrystalline networks are prepared starting from poly(ε-caprolactone) and properly combining electrospinning and sol–gel reactions. The mats are obtained as continuous, randomly oriented micrometric fibers with different network densities. The systems are subjected to thermomechanical cycles to investigate their one-way and two-way shape memory behavior. One-way tests aim at exploring the effects of the deformation temperature on the materials response, with particular interest to the less investigated cold-working conditions (i.e., deformation temperature below Tm). The materials display two-way shape memory capabilities (i.e., the ability to change between two distinguished shapes upon heating and cooling under a fixed nonzero stress) and the effect of the applied stress is explored. The shape memory characterization is accompanied by an ex situ SEM analysis, to describe the concurrent microstructural evolution during the macroscopic shape variation, and by the assessment of their biocompatibility, to explore the suitability of the nonwovens for biomedical applications. (Figure presented.).

2017 - Nanocomposites based on poly(L-lactide)/poly(epsilon-caprolactone) blends with triple-shape memory behavior: Effect of the incorporation of graphene nanoplatelets (GNps) [Articolo su rivista]
Khademeh Molavi, Fatemeh; Ghasemi, Ismaeil; Messori, Massimo; Esfandeh, Masoud

In this study, a novel thermally actuated triple-shape memory polymer (triple-SMP) based on poly(L-lactide) (PLA)/poly(ε-caprolactone) (PCL)/graphene nanoplatelets (GNps) nanocomposite was prepared by facile solution mixing method and the design of which was based on two well-separated melting temperatures. In order to improve the dispersion of GNps in the matrix, functionalization reactions were carried out on the GNPs surface. Functionalization was confirmed by various techniques including FTIR, Raman and TGA analysis. TEM micrographs revealed an exfoliated morphology for the functionalized GNps (FGNps) and a homogenous dispersion in the matrix. The crystallinity behaviour of nanocomposites was investigated by DSC and variable temperature XRD (VT-XRD) analysis and an increase in crystallinity was observed. Dynamic mechanical analysis (DMA) showed that the presence of FGNps improves the fixity and recovery ratios because of increase in crystallinity and thermal conductivity. The best shape memory behavior was obtained for PLA50/PCL50/FGNp 1.5 nanocomposite.

2017 - Non-hydrolytic sol–gel synthesis and reactive suspension method: an innovative approach to obtain magnetite–epoxy nanocomposite materials [Articolo su rivista]
Sciancalepore, Corrado; Bondioli, Federica; Messori, Massimo

Innovative magnetite–epoxy nanocomposites were prepared starting from magnetite nanoparticles suspended in alcoholic or amino reactive solvents, synthesized by non-hydrolytic sol–gel process from iron (III) acetylacetonate. The obtained suspensions, also synthesized using microwave heating, were mixed with an epoxy monomer (bisphenol A diglycidyl ether, DGEBA), and the formulations were subsequently cured. The thermally activated ring-opening polymerization produced a three-dimensional network in which the suspending medium was covalently linked to the epoxy network according to the chain or step polymerization mechanisms during the cross-linking reaction. This synthetic strategy allowed to obtain nanocomposites in which the nanoparticles play an active role in the polymeric structure, affecting the structural (mechanical and thermal) and functional (magnetic) properties of the final system. The presence of magnetite nanoparticles in the composite resulted in distinct reinforcing effects, acting as rigid filler and/or as cross-linking point, depending on the different chemical environment at the nanoparticle–polymer interphase.

2017 - Organic-inorganic nanocomposites prepared by reactive suspension method: investigation on filler/matrix interactions and their effect on the nanoparticles dispersion [Articolo su rivista]
Spinella, Alberto; Bondioli, Federica; Nasillo, Giorgio; Renda, Vincenzo; Caponetti, Eugenio; Messori, Massimo; Morselli, Davide

Epoxy resin/TiO2 nanocomposites prepared by both reactivesuspension method, based on in situ synthesis, and conventional mechanical mixing are analysed by solid-state nuclear magnetic resonance and transmission electron microscopy in order to have a deeper insight into the nature of interactions at the polymer/particle interface and their effect on the nanoparticles dispersion. Specifically, solid-state nuclear magnetic resonance experiments showed that the nanoparticles, synthesized by reactive suspension method, can efficiently link the matrix by hydrogen bonds forming a hybrid organic-inorganic 3D network. Such evidences strongly supports our previously reported theory, in which the nanoparticles in situ synthesized by reactive suspension method act not only as rigid filler, but also as actual cross-linking points, dramatically improving the mechanical properties of the polymeric matrix. Moreover, as revealed by transmission electron microscopy investigations, the formation of such hydrogen bonds significantly affect also the nanoparticles distribution, thanks to a stabilizing effect on the nanoparticles’ surface that prevents their aggregation and improves their dispersion.

2017 - Poly(ethylene glycol)-based shape-memory polymers [Articolo su rivista]
Boumezgane, Oussama; Messori, Massimo

Poly(ethylene glycol) (PEG) blends photo-curable and thermal activated shape-memory polymers (SMPs), with different activation temperature (Tswitch), have been synthesized and characterized. PEG blends with different molecular weights were chain-end functionalized with isocyanate ethyl methacrylate and photo-cured with UV lamp. Degree of cross-linking of the blend network, determined by gel content measurement, resulted as higher than 95%. The thermal and thermomechanical properties of these SMPs PEG blends were characterized by differential scanning calorimetry and dynamic mechanical analysis. The shape-memory properties of the networks were quantified using thermomechanical three-point bending experiments and showed strain fixity rates higher than 99% and a minimum strain recovery ratio of 82%.

2017 - Surface Modification of Polymers: Chemical, Physical, and Biological Routes [Capitolo/Saggio]
Fabbri, Paola; Messori, Massimo

Modification of Polymer Properties provides, for the first time, in one title, the latest information on gradient IPNs and gradient copolymers. The book covers the broad range of polymer modification routes in a fresh, current view representing a timely addition to the technical literature of this important area. Historically, blends, copolymers, or filled polymers have been developed to meet specific properties, or to optimize the cost/properties relationship. Using the gradient structure approach with conventional radical polymerization, it has been shown that it is possible to optimize properties if appropriate gradients in the composition of copolymer chains are obtained. An overview of the gradient structure approach for designing polymers has not appeared in the recent literature and this title covers the different methods used to modify properties, offering the whole range of ways to modify polymers in just one volume and making this an attractive option for a wide audience of practitioners. The approach for each chapter is to explain the fundamental principles of preparation, cover properties modification, describe future research and applications as examples of materials that may be prepared for specific applications, or that are already in use, in present day applications. The book is for readers that have a basic background in polymer science, as well as those interested in the different ways to combine or modify polymer properties.

2017 - Synthesis and characterization of scratch-resistant hybrid coatings based on non-hydrolytic sol-gel ZrO2 nanoparticles [Articolo su rivista]
Tana, Francesca; Messori, Massimo; Contini, Davide; Cigada, Alberto; Valente, Teodoro; Variola, Fabio; De Nardo, Luigi; Bondioli, Federica

Hybrid transparent coatings based on zirconia nanoparticle fillers and epoxy resin were designed to increase scratch resistance of commodity polymers without impairing their optical properties. Suspensions of nano-crystalline ZrO2 in benzyl alcohol were synthesized via a versatile non-hydrolytic sol-gel process using ZrCl4 as precursor. The obtained ZrO2 nanoparticles showed a crystalline structure attributable to a tetragonal phase and an average particle size of 2 nm. ZrO2 nanoparticles, suspended in tert-butanol, were mixed with a commercial epoxy resin (5 and 10%wt.). The organic solvent was then evaporated and hybrid composites were deposited on polycarbonate and poly(methyl methacrylate). The obtained coatings showed a homogeneous adhesion and a negligible effect on the transparency of these polymers. An increased scratch-resistance was obtained by increasing the ZrO2 nanoparticles content.

2016 - A scratch resistant yet healable automotive clearcoat containing hyperbranched polymer and POSS nanostructures [Articolo su rivista]
Yari, H.; Mohseni, M.; Messori, Massimo

In this paper a typical acrylic melamine clearcoat has been modified with hyperbranched polymer and polyhedral oligomeric silsesquioxane nanostructures to simultaneously enhance its scratch resistance and healing ability. Scratch behaviour and healing performance of clearcoats were investigated by micro-scratching and confocal profilometry techniques. Various techniques were employed to correlate scratch resistance and healing enhancements to the various mechanical and structural characteristics of nano clearcoats. Enhanced scratch resistance was attributed to the increased elastic recovery of the clearcoats in the presence of nano-structured modifiers. In addition, the improved self-healing performance was assigned to the partial replacement of covalent cross-links with physical ones i.e. H-bonding. Simultaneous reinforcement with covalent and physical linkages led to the formation of a more flexible network which maintains its mechanical integrity at ambient temperature and also provides dynamic chain movements for thermal healing treatments at high temperature.

2016 - Bioactive nanocomposites for dental application obtained by reactive suspension method [Articolo su rivista]
Boumezgane, Oussama; Bondioli, Federica; Bortolini, Sergio; Natali, Alfredo; Boccaccini, Aldo R.; Boccardi, Elena; Messori, Massimo


2016 - Facile fabrication of shape memory poly(ϵ-caprolactone) non-woven mat by combining electrospinning and sol-gel reaction [Articolo su rivista]
Merlettini, Andrea; Pandini, Stefano; Agnelli, Silvia; Gualandi, Chiara; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Focarete, Maria Letizia

Poly(ϵ-caprolactone)-based non-woven fibrous mats showing excellent one-way shape memory properties were obtained through a straightforward approach by combining electrospinning process and sol-gel reaction. A solution of partially crosslinked α,ω-triethoxysilane-terminated poly(ϵ-caprolactone) was used to obtain bead-free fibers through electrospinning. Non-woven mats with different crosslinking degrees have been prepared and the effect of the different crosslinking extent and of the microfibrous structure were correlated to the mechanical and shape memory properties of the material. The evolution of fiber architecture within the non-woven mat following deformation and shape memory cycles was also investigated.

2016 - Graphene nanoplatelets dispersion in poly(l-lactic acid): preparation method and its influence on electrical, crystallinity and thermomechanical properties [Articolo su rivista]
Lashgari, Soheila; Karrabi, Mohammad; Ghasemi, Ismaeil; Azizi, Hamed; Messori, Massimo

Poly(l-lactic acid) (PLLA)/graphene nanoplatelets (GnP) nanocomposites were prepared through solvent casting and coagulation methods. The better dispersion of graphene was achieved by ultrasounds and its effect on crystallinity, thermomechanical and electrical properties of PLLA were studied and compared in both methods. Differential scanning calorimetry (DSC) was used to investigate the crystallinity of PLLA and its composites. Field emission gun scanning electron microscope (FEG-SEM) and wide-angle X-ray scattering (WAXS) were employed to characterize the microstructure of PLLA crystallites. Dynamic mechanical thermal analysis (DMTA) was performed to study the thermomechanical properties of the nanocomposites. FEG-SEM images illustrated finer dispersion of GnP in samples obtained by coagulation method with respect to solvent casting method. Graphene imparted higher electrical conductivity to nanocomposites obtained by solvent casting under ultrasound due to better formation of graphene network. DSC thermograms and their resulting data showed positive effects of GnP on crystallization kinetics of PLLA in both methods enhanced by the nucleating effect of graphene particles. Meanwhile, the effect of GnP, as nucleating agent, was more prominent in samples produced by coagulation method without utilization of ultrasounds. WAXS patterns represented the same characteristic peaks of PLLA in nanocomposite specimens suggesting similar crystalline structure of PLLA in presence of graphene, and the intensified peaks of nanocomposites compared to neat PLLA confirmed the DSC results regarding its improved crystallinity. Graphene increased storage modulus in rubbery region and glass transition temperature of nanocomposites in the coagulation method due to restricted mobility of PLLA chains.

2016 - Hydrophobic Scratch Resistant UV-Cured Epoxy Coating [Articolo su rivista]
Sangermano, Marco; Perrot, Alexandre; Gigot, Arnaud; Rivolo, Paola; Pirri, Fabrizio; Messori, Massimo

A selective modification of the surface properties of UV-cured epoxy films was achieved, with an important enhancement of hydrophobicity and scratch resistance, by dispersion on the UV-curable formulations of fluorinated functionalized silica particles. The photopolymeriza- tion process was investigated and the films were fully characterized. Contact angle measurements with water on UV-cured films showed a linear increase of the contact angle of cross-linked films by increasing the functionalized SiO2 content in the photocurable formulation. Also, a consistent and linear improvement of penetration resistance was noted in terms of penetration depth by increasing the fluorinated functionalized silica content.

2016 - Organic-inorganic hybrid coatings with enhanced scratch resistance properties obtained by the sol-gel processMessori, M.a, Sangermano, M. [Capitolo/Saggio]
Messori, M.; Sangermano, M.

2016 - Shape memory nanocomposite of poly(L-lactic acid)/graphene nanoplatelets triggered by infrared light and thermal heating [Articolo su rivista]
Lashgari, S.; Karrabi, M; Ghasemi, I.; Azizi, H.; Messori, Massimo; Paderni, Katia

In this study, the effect of graphene nanoplatelets (GNPs) on the shape memory properties of poly(L-lactic acid) (PLLA) was studied. In addition to thermal activation, the possibility of infrared actuating of thermo-responsive shape memory PLLA/GNPs nanocomposite was investigated. The incorporated GNPs were expected to absorb infrared wave’s energy and activate shape memory PLLA/GNPs. Different techniques such as differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), field emission gun scanning electron microscope (FEG-SEM) and dynamic mechanical thermal analysis (DMTA) were used to characterize samples. DSC and WAXD results indicated that GNPs augmented crystallinity due to nucleating effect of graphene particles. GNPs improved both thermal and infrared activating shape memory properties along with faster response. Pure shape memory PLLA was slightly responsive to infrared light and its infrared actuated shape recovery ratio was 86% which increased to more than 95% with loading of GNPs. Drastic improvement in the crystallinity was obtained in nanocomposites with lower GNPs contents (0.5 and 1 wt%) due to finer dispersion of graphene which resulted in more prominent mechanical and shape memory properties enhancement. Infrared activated shape memory PLLA/GNPs nanocomposites can be developed for wireless remote shape control of smart medical and bio-systems.

2016 - Synthesis and characterization of polyhedral oligomeric titanized silsesquioxane: A new biocompatible cage like molecule for biomedical application [Articolo su rivista]
Yahyaei, Hossein; Mohseni, Mohsen; Ghanbari, Hossein; Messori, Massimo

Organic-inorganic hybrid materials have shown improved properties to be used as biocompatible coating in biomedical applications. Polyhedral oligomeric silsesquioxane (POSS) containing coatings are among hybrid materials showing promising properties for these applications. In this work an open cage POSS has been reacted with a titanium alkoxide to end cap the POSS molecule with titanium atom to obtain a so called polyhedral oligomeric metalized silsesquioxane (POMS). The synthesized POMS was characterized by FTIR, RAMAN and UV-visible spectroscopy as well as 29Si NMR and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) techniques. Appearance of peaks at 920 cm- 1 in FTIR and 491 cm- 1 and 1083 cm- 1 in Raman spectra confirmed Si-O-Ti linkage formation. It was also demonstrated that POMS was in a monomeric form. To evaluate the biocompatibility of hybrids films, pristine POSS and synthesized POMS were used in synthesis of a polycarbonate urethane polymer. Results revealed that POMS containing hybrid, not only had notable thermal and mechanical stability compared to POSS containing one, as demonstrated by DSC and DMTA analysis, they also showed controlled surface properties in such a manner that hydrophobicity and biocompatibility were both reachable to give rise to improved cell viability in presence of human umbilical vein endothelial cells (HUVEC) and MRC-5 cells.

2016 - The two-way shape memory behaviour of crosslinked poly(e-caprolactone) systems with largely varied network density [Articolo su rivista]
Pandini, S.; Dioni, D.; Paderni, Katia; Messori, Massimo; Toselli, M.; Bontempi, E.; Ricco, T.

The two-way shape memory behaviour of semicrystalline networks was investigated on systems based on poly(e-caprolactone) featuring significantly different network architecture. Crosslinked poly(e-caprolactone)s were prepared by thermal curing from methacrylic end-capped linear chains having various methacrylation degrees. By conveniently reducing the methacrylation degree, the crosslink density of cured materials was varied over a range of one order of magnitude, leading to comparable changes in the material compliance in the rubbery region, but only to moderate variations in melting and crystallization temperatures (Tm and Tc) and in the crystallinity content. When subjected to constant non-zero stress and to cooling–heating cycles from above Tm to below Tc, the materials undergo a reversible two-way elongation–contraction effect, whose extent depends on material structure and applied stress. The structural changes in the crystalline phase accompanying the cooling-induced elongation were studied through differential scanning calorimetry and X-ray diffraction analyses. The elongation process involves different contributions of entropy- and crystallization-driven processes, whose amounts were investigated as a function of the loading conditions and the molecular architecture. The role of the network density towards a controlled two-way response is evidenced, showing that a proper value of the crosslink density has to be identified to maximize the two-way elongation capabilities.

2015 - Epoxy nanocomposites functionalized with in situ generated magnetite nanocrystals: Microstructure, magnetic properties, interaction among magnetic particles [Articolo su rivista]
Sciancalepore, Corrado; Bondioli, Federica; Messori, Massimo; Barrera, Gabriele; Tiberto, Paola; Allia, Paolo

Magnetite nanoparticles in the range 7-10.5 nm were prepared by non hydrolytic sol-gel (NHSG) process in the presence of benzyl alcohol in different concentrations. The suspensions were mixed with bisphenol A diglycidyl ether (DGEBA) and cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. Magnetite nanoparticles and epoxy nanocomposites were characterized by structural, chemical and magnetic techniques. A procedure of data analysis is proposed to determine value, sign and surface contribution of the magnetic anisotropy of nanoparticles by comparing the information gained from field-cooled/zero-field-cooled magnetization curves and TEM images. Above blocking temperature, the nanoparticles dispersed in the epoxy resin give rise to an interacting superparamagnetic system and follow the corresponding scaling law. A model explains why the magnetic interaction energy depends not only on nanoparticle concentration in the epoxy but also on concentration fluctuations, being larger in samples where the nanoparticle dispersion is not uniform.

2015 - Epoxy networks reinforced with TiO2 generated by nonhydrolytic sol-gel process: a comparison betweenin situandex situsyntheses to obtain filled polymers [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; Sangermano, Marco; Messori, Massimo

Titania nanoparticles suspended in benzyl alcohol (BzOH) were generated by nonhydrolytic sol–gel process starting from titanium tetrachloride. The obtained suspensions were mixed with 3,4-epoxycyclohexylmethyl-3,4-epoxycy- clohexanecarboxylate epoxy resin, and the formulations were cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. The thermally activated cationic ring-opening polymerization produced a three-dimensional network in which the suspending medium BzOH was covalently linked to the epoxy network according to the “activated monomer” mechanism during the propagation step. The presence of titania nanoparticles resulted in a reinforcing and stiffening effect due to both their hydrodynamic effect and, most important, a significantly higher cross-linking density of the composite material with respect to the unfilled epoxy resin. A comparison with similar composites obtained by physical incorporation of preformed titania particles was also reported in order to compare the in situ and ex situ filler generation for preparing nanocomposites.

2015 - Hybrid epoxy networks from ethoxysilyl-modified hyperbranched poly(ethyleneimine) and inorganic reactive precursors [Articolo su rivista]
Acebo, Cristina; Fernández Francos, Xavier; Santos, José Ignacio; Messori, Massimo; Ramis, Xavier; Serra, Àngels

New epoxy–silica hybrid coatings were prepared by a dual process consisting of a sol–gel process using tetraethoxysilane (TEOS) or 3-glycidyloxypropyl trimethoxysilane (GPTMS) in the presence of hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends (PEI-Si) followed by a homopolymerization of diglycidylether of bisphenol A (DGEBA) using 1-methylimidazole (1-MI) as anionic initiator. The influence of the amount of TEOS and GPTMS in the characteristics of the coating was examined. Thin transparent films were obtained and their morphology was observed by transmission electron microscopy (TEM). The hydrolytic condensation was confirmed by 29Si NMR studies. Cage-like nanometric structures were formed in case of adding GPTMS and bigger silica particles on adding TEOS to the formulation. Thermal stability was evaluated by thermo- gravimetry and the scratch resistance properties were also investigated, showing an improvement in resistance to break and to detachment in all the coatings containing GPTMS.

2015 - Influence of in situ-generated silica nanoparticles on EPDM morphology, thermal, thermomechanical, and mechanical properties [Articolo su rivista]
Mokhothu, T. H.; Luyt, A. S.; Morselli, D.; Bondioli, F.; Messori, Massimo

Silica nanoparticles were synthesized by means of a sol–gel method and generated in ethylene propylene diene monomer rubber (EPDM) by in situ synthesis. The properties were determined using scanning elec- tron microscopy, attenuated total reflectance Fourier- transform infrared spectroscopy, thermogravimetric analysis, tensile testing, dynamic mechanical analysis, swelling tests, and gel content determination. The silica particles were homogenously dispersed in the EPDM matrix, with the presence of agglomerates, especially for high silica contents. The swelling experi- ments showed a decrease in the crosslinking density of the vulcanized rubber due to the presence of the silica nanoparticles. The mechanical properties, how- ever, were significantly improved by the presence of the stiff silica nanoparticles. The effect of the amount of silica on the thermomechanical properties and ther- mal degradation of EPDM was also investigated. The presence of silica showed an increase in the storage and loss moduli at high temperatures, probably due to the increasing filler content. The thermal degradation analysis showed that the presence of silica particles incorporated in the EPDM matrix had no significant influence on the thermal stability of the composites.

2015 - Toughened acrylic/melamine thermosetting clear coats using POSS molecules: Mechanical and morphological studies [Articolo su rivista]
Yari, H.; Mohseni, M.; Messori, Massimo

This work attempts to introduce polyhedral oligomeric silsesquioxane compounds as a novel toughening agent for thermosetting systems. For this purpose, an acrylic/melamine thermosetting system was modified by OH-functional silsesquioxane nano-cage. Mechanical and thermo-mechanical behavior of resultant nanocomposites were studied by tensile and DMTA techniques. It was found that low content of silsesquioxane building blocks is sufficient to shift the mechanical behavior of the matrix from a brittle character to a flexible tough one. Various morphological techniques (SEM and TEM equipped with elemental analyzer together with XRD) were also utilized to clarify how nano-cages have been oriented within the matrix. It was revealed that nano-cages have been well dispersed in a molecular scale within the thermosetting network. The good dispersion of silsesquioxane compounds was assigned to the high compatibility within the matrix owing to their compact structure and OH-functional groups available on the cage.

2015 - UV-Cured Functional Coatings [Capitolo/Saggio]
Sangermano, M.; Roppolo, I.; Messori, Massimo


2014 - CHAPTER 7. UV-Cured Functional Coatings [Capitolo/Saggio]
M., Sangermano; I., Roppolo; Messori, Massimo

UV-cured functional coatings review

2014 - Compositi a memoria di forma a base di poli(ε-caprolattone) [Relazione in Atti di Convegno]
Messori, Massimo; Paderni, Katia; M., Toselli; S., Pandini


2014 - EPDM rubber reinforced with titania generated by nonhydrolytic sol-gel process [Articolo su rivista]
Paderni, Katia; Morselli, Davide; Bondioli, Federica; Luyt, Adriaan S.; Mokhothu, Thabang H.; Messori, Massimo

EPDM rubber was reinforced with titania in situ generated by using a nonhydrolytic sol-gel (NHSG) process starting from TiCl4 as titania precursor and tert-butanol as oxygen donor. Titania particles in anatase form and with average diameter of 6 nm were synthesized via NHSG route and then the same procedure was adopted in presence of EPDM rubber to obtain composites containing up to 30 wt% of filler. Extraction and equilibrium swelling tests suggested an interfering effect of the NHSG reaction on the vulcanization process of the rubber resulting to a crosslink density which decreased in the presence of titania. Quasistatic and dynamic-mechanical characterizations indicated that the presence of titania as rigid filler in both the unvulcanized and vulcanized EPDM matrix led to a significant increase in stiffness and stress at break. The experimental values of modulus were systematically higher than the values predicted by classical equations suggesting an additional stiffening contribution deriving from the molecular interaction between the rubber and the filler.

2014 - Epoxy resins reinforced with TiO2 generated by non-hydrolytic sol-gel process [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; Marco, Sangermano; Ignazio, Roppolo; Messori, Massimo

Innovative epoxy-titania nanocomposites were prepared starting from titania nanoparticles suspended in benzyl alcohol (BzOH) generated by nonhydrolytic sol–gel process from TiCl4. The obtained suspensions were mixed with an epoxy resin (bisphenol A diglycidyl ether, DGEBA) and the formulations were cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. The thermally activated cationic ring-opening polymerization produced a three-dimensional network in which the suspend- ing medium BzOH was covalently linked to the epoxy network according to the “activated monomer” mechanism during the propa- gation step. The presence of titania nanoparticles resulted in a reinforcing and stiffening effect due to both their hydrodynamic effect and, most important, a significantly higher cross-linking density of the composite material with respect to the unfilled epoxy resin.

2014 - Evaluation of the shape memory performances of poly(ε-caprolactone)- based tubular devices for potential biomedical applications [Relazione in Atti di Convegno]
Pandini, Stefano; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Cambiaghi, Danilo; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Riccò, Theonis

The shape memory behavior of tubular specimens based on crosslinked poly(epsilon-caprolactone) was investigated in order to evaluate their ability i) to restore their shape after being folded in a more compact one, and ii) to exert stress under external confinement (recovery stress). The specimens were prepared following different crosslinking methodologies and with different network densities, in order to tailor the material response in terms of transformation temperatures and recovery stress capabilities. The devices are able to fully recover their shape once heated close to the melting temperature and to exert moderate stresses, that may be controlled through thickness and crosslink density, and whose values were employed to develop a new testing apparatus for the measurement of radial dilation capabilities.

2014 - Insights into shape-memory poly(ε-caprolactone) materials by solid-state NMR [Articolo su rivista]
Borsacchi, Silvia; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Pilati, Francesco; Geppi, Marco

Polymeric materials showing shape-memory behavior are attracting large interest especially in the field of biomaterials. Despite the large number of studies aimed at charaterizing macroscopic features, detailed investigations of properties at the nanometric scale and molecular level are still very few. In this work we present a multinuclear and multitechnique solid-state NMR investigation on recently developed hybrid materials formed by sol-gel cross-linked alkoxysilane terminated poly(e-caprolactone), showing very interesting shape-memory behavior. By investigating several spectral and relaxation properties of Si-29, C-13, and H-1 nuclei present in the hybrid material, we could characterize and compare the structural, dynamic, and phase properties of a sample fixed in a stretched temporary shape with those of a sample in the permanent shape. Interesting differences could be observed: in particular, the sample fixed in the temporary shape showed a larger amount (40% instead of 35%) of crystalline phase and amorphous domains in which polymeric chains experienced a more restricted molecular mobility, as inferred from proton T-2 values. Moreover, from C-13 spectra recorded by varying the orientation of the sample with respect to the direction of the magnetic field, it was possible to clearly detect that about 90% of PCL chains, mainly in the crystalline domains, but also in the amorphous ones, were strongly aligned along the stretching direction. If subjected to heating, so to remove the temporary shape, the sample showed a melting temperature a few degrees higher, a sligthly more rigid melt phase, and a complete loss of molecular alignment.

2014 - Mass transport in hybrid PTMSP/silica membranes [Articolo su rivista]
Galizia, Michele; De Angelis, Maria Grazia; Messori, Massimo; Sarti, Giulio C.

Hybrid silica/poly(trimethylsilylpropyne) (PTMSP) membranes in which the silica particles are generated in the polymer solution with a sol gel reaction from a tetraethoxysilane (TEOS) precursor were fabricated. The membranes are characterized with microscopic, thermogravimetric, and pycnometric analysis; their sorption and diffusion properties with respect to n-C-4 and n-C-5 vapors are also measured at 25 degrees C. A significant reduction of the polymer specific volume, organic vapor solubility, and diffusivity is observed after incorporation of silica, according to a combination of free volume filling and compressive constraints. The behavior of the hybrid membranes (HM) is opposite that of mixed matrix membranes (MMM) obtained by physical mixing of preformed silica nanoparticles into PTMSP solutions, which show, on the contrary, free volume, vapor solubility, and diffusivity values higher than pure PTMSP. The hybrid membranes are characterized by larger silica domains than mixed matrix ones. Remarkably, however, the transport behavior of both types of membranes can be interpreted, by the same theoretical background, on the basis of a single structural parameter, namely the density of the polymer phase. This parameter allows a direct estimation of the variation of free volume and vapor solubility and diffusivity in both types of membranes, through a NELF/free volume approach.

2014 - Multilayer films composed of conductive poly(3-hydroxybutyrate)/carbon nanotubes bionanocomposites and a photoresponsive conducting polymer [Articolo su rivista]
Luca, Valentini; Fabbri, Paola; Messori, Massimo; DEGLI ESPOSTI, Micaela; Silvia Bittolo, Bon

In order to develop new electronic devices, it is necessary to find innovative solutions to the eco-sustainability problem of materials as substrates for circuits. We realized a photoresponsive device consisting of a semiconducting polymer film deposited onto optically semitransparent and conductive biodegradable poly(3-hydroxybutyrate) (PHB)/carbon nanotube (CNT) substrates. The experiments indicated that the PHB-CNT bionanocomposite substrate behaves as an optical window trapping electric charges produced by the photoexcitation of the semiconducting polymer. Such PHB-CNT functional substrates are expected to be attractive for eco-friendly electronics.

2014 - Novel epoxy-silica hybrid coatings by using ethoxysilyl-modified hyperbranched poly(ethyleneimine) with improved scratch resistance [Articolo su rivista]
Cristina, Acebo; Xavier Fernández, Francos; Messori, Massimo; Xavier, Ramis; Àngels, Serra

A new hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends has been synthesized and characterized and then used in epoxy formulations to generate new organic/inorganic hybrid materials. Formulations of different proportions of diglycidylether of bisphenol A and the prepared ethoxysilylated hyperbranched poly(ethyleneimine) were maintained in a thermostatized controlled humidity chamber to form the inorganic silica network by a sol-gel process and then the epoxy resin was cured at higher temperature using 1-methylimidazole as anionic initiator. Transparent hybrid materials were prepared and characterized by thermal tests and their fine morphology was observed by transmission electron microscopy. The formation of the silicon structure was confirmed by 29Si NMR studies. Thermal stability was evaluated by thermogravimetry. Improvement of the mechanical coating performance was confirmed by scratch measurement.

2014 - Preparation and characterization of EPDM/silica composites prepared through non-hydrolytic sol-gel method in the absence and presence of a coupling agent [Articolo su rivista]
T. H., Mokhothu; A. S., Luyt; Messori, Massimo

Ethylene propylene diene monomer (EPDM) rubber composites containing in situ generated silica particles was prepared through a non-hydrolytic sol-gel (NHSG) method with silicon tetrachloride as precursor. The silica particles were homogenously dispersed in the EPDM matrix, but there were agglomerates at high silica contents. The swelling experi- ments showed a decrease in the crosslinking density of the vulcanized rubber due to the presence of the silica particles for both the composites prepared in the presence and absence of a coupling agent, bis-[-3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT). Unlike the composites prepared through a hydrolytic sol-gel (HSG) method with TEOS as precursor, the TESPT did not seem to take part in the sol-gel reaction. The presence of TESPT influenced the interaction and dispersion of the sil- ica particles in the EPDM matrix, which gave rise to increased thermal stability of the EPDM when compared to the com- posites prepared in the absence of TESPT. However, ethylene chloride and TESPT evaporated from the samples at temperatures below the EPDM decomposition range. The values of the Nielsen model parameters, that gave rise to a good agreement with the experimentally determined Young’s modulus values, indicated improved dispersion and reduced size of the silica aggregates in the EPDM matrix. There was also good agreement between the storage modulus and Young’s mod- ulus values. The filler effectiveness (Factor C) indicated a mechanical stiffening effect and a thermal stability contribution by the filler, while the damping reduction (DR) values confirmed that the EPDM interacted strongly with the well dispersed silica particles and the polymer chain mobility was restricted. The tensile properties, however, were in some cases worse than those for the samples prepared through the HSG method in the presence of TEOS.

2014 - Preparation of scratch resistant superhydrophobic hybrid coatings by sol-gel process [Articolo su rivista]
Taurino, Rosa; Fabbri, Elena; Pospiech, Doris; Synytska, Alla; Messori, Massimo

Organic-inorganic hybrid coatings on glass substrates with superhydrophobic properties and with improved scratch resistance were obtained by means of applying a multilayer approach including multiple sol-gel processes. The coatings exhibited a water contact angle (WCA) higher than 150 degrees. Ultraviolet (UV)-curable vinyl ester resins and vinyltriethoxysilane (VTEOS) as coupling agent were employed to increase the adhesion between substrate and the inorganic layers. The surfaces were characterized by means of dynamic contact angle and roughness measurements. Indeed, the occurrence of superhydrophobic behavior was observed. The scratch resistance of the hybrid coatings was tested to evaluate the adhesion of the coatings to the glass substrate. The proposed preparation method for scratch resistant, mechanically stable, superhydrophobic coatings is simple and can be applied on large areas of different kinds of substrates.

2014 - Preparazione e caratterizzazione di idrogeli nanocompositi a base di poli(acrilonitrile-co-acrilammide) contenenti grafene ossido [Relazione in Atti di Convegno]
Bisi, Francesca; Messori, Massimo; F., Pilati; M., Toselli


2014 - Reinforcement of EPDM rubber with in situ generated silica particles in the presence of a coupling agent via a sol–gel route [Articolo su rivista]
T. H., Mokhothu; A. S., Luyt; Messori, Massimo

Ethylene propylene diene monomer rubber (EPDM)-silica (SiO2) composites were pre- pared by means of an in situ sol–gel process with tetraethoxysilane (TEOS) as precursor and bis-[-3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) as coupling agent. Homogenous dispersion of the silica particles was observed in all cases, as well as good adhesion be- tween the filler and the matrix. The swelling and gel content results indicated that the number of crosslinks decreased, while the network was still extensive enough to maintain the high gel content. These results indicate that the coupling agent acted as a bridge be- tween the hydrophilic silica and the hydrophobic rubber and enhanced the rubber-silica interactions. This enhanced interaction gave rise to increased thermal stability of the EPDM. The values of the Nielsen model parameters, which gave rise to good agreement with the experimentally determined Young’s modulus values, indicate improved dispersion and reduced size of silica aggregates in the EPDM matrix. Good agreement was found between the storage modulus and Young’s modulus values. The filler effectiveness (Factor C) indicated a mechanical stiffening effect and a thermal stability contribution by the filler, while the damping reduction (DRNorm) values confirmed that the EPDM interacted strongly with the well dispersed silica particles, and the polymer chain mobility was restricted.

2014 - Resine epossidiche rinforzate con titania generata con processo sol-gel non idrolitico: un confronto fra generazione in situ ed ex situ [Relazione in Atti di Convegno]
Messori, Massimo; D., Morselli; F., Bondioli; M., Sangermano


2014 - Shape Memory Properties of PBS-Silica Hybrids [Articolo su rivista]
Paderni, Katia; Fabbri, Paola; Maurizio, Toselli; Messori, Massimo

A series of novel Si–O–Si crosslinked organic/inorganic hybrid semi-crystalline polymers with shape memory properties was prepared from alkoxysilane-terminated poly(butylene succinate) (PBS) by water-induced silane crosslinking under organic solvent-free and catalyst-free conditions. The hydrolyzation and condensation of alkoxysilane end groups allowed for the generation of silica-like crosslinking points between the polymeric chains, acting not only as chemical net-points, but also as inorganic filler for a reinforcement effect. The resulting networks were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic-mechanical analysis (DMA) and tensile and shape memory tests to gain insight into the relationship between the polymeric structure, the morphology and the properties. By controlling the molecular weight of the PBS precursor, a fine tuning of the crosslinking density and the inorganic content of the resulting network was possible, leading to different thermal, mechanical and shape memory properties. Thanks to their suitable morphology consisting of crystalline domains, which represent the molecular switches between the temporary and permanent shapes, and chemical net-points, which permit the shape recovery, the synthesized materials showed good shape memory characteristics, being able to fix a significant portion of the applied strain in a temporary shape and to restore their original shape above their melting temperature.

2014 - Tailored one-way and two-way shape memory capabilities of poly(ε-Caprolactone)-based systems for biomedical applications [Articolo su rivista]
Pandini, Stefano; Riccò, Theonis; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Cambiaghi, Danilo; Toselli, Maurizio; Paderni, Katia; Messori, Massimo; Pilati, Francesco; Chiellini, Federica; Bartoli, Cristina

This paper investigates the shape memory capabilities of semicrystalline networks, focusing the attention on poly(epsilon-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large "temporary" shape configurations, and the easy tailoring of the transformation temperatures. The materials were prepared with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicrystalline systems was prepared by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biological tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystallization temperatures. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mechanical cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory experiments were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a constant load and of a heating/cooling cycle from above melting to below the crystallization temperature, leading to a reversible elongation/contraction effect, involving maximum strain changes up to about 80%, whose extent may be controlled through the crosslink density.

2014 - The network density as tailoring parameter for the two-way shape memory response of crosslinked poly(ε-caprolactone) [Relazione in Atti di Convegno]
Pandini, Stefano; Dioni, Daniele; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Riccò, Theonis

The "two-way" shape memory response of semicrystalline networks was studied on poly(epsilon-caprolactone)-based systems, crosslinked by thermal curing of methacrylic end-capped linear chains. By changing the methacrylation degree of the precursors, it was possible to vary the network density over one order of magnitude, without any remarkable change in their transition temperatures and crystallinity content. When subjected to a constant stress and to a cooling-heating cycle from above T-m to below T-c, the materials display reversible two-way shape memory capabilities, consisting in a cyclic elongation-contraction effect, which involves significant variations of strain. Two different cooling induced elongational processes are evidenced, one due to entropy elasticity and the other to a crystallization driven effect. The amount of elongation that may be achieved depends on the network density and on the applied stress, and it is maximized for systems with a crosslink density that allows to exploit both the entropy-and the crystallization-induced effect.

2014 - Thermo-mechanical and impact properties of polymeric foams used for snow sports protective equipment [Relazione in Atti di Convegno]
Nicotra, Marco; Moncalero, Matteo; Messori, Massimo; Fabbri, Elena; Fiorini, Maurizio; Colonna, Martino

The thermo-mechanical and impact properties of materials used for hard-shell and soft-shell back protectors have been analysed in order to understand the mechanism of action of the foams used for protective equipment. Dynamical mechanical analysis has shown that materials used for soft-shell protectors present frequency-sensitive properties that permit to have a soft response when stressed at low speed and a hard response when subjected to a high-speed impact. Furthermore, by means of drop weight impact tests, the shock absorbing characteristics of the materials have been investigated at two temperatures pointing out the differences between soft and hard-shell protectors; in addition it has been demonstrated that the materials used for soft-shell protectors maintain their protective properties after multi-impacts on the same point.

2014 - Tribological properties and scratch healing of a typical automotive nano clearcoat modified by a polyhedral oligomeric silsesquioxane compound [Articolo su rivista]
Yari, H.; Mohseni, M.; Messori, Massimo; Ranjbar, Z.

The present work has studied the influence of an OH-functionalized polyhedral oligomeric silsesquioxane(POSS) nano-structure on the scratch resistance of a typical acrylic melamine clearcoat. Scratch resistance and the healing ability of clearcoats were investigated by micro-scratch studies and confocal profilometry techniques. In addition, hardness and thermo-mechanical characteristics of clearcoats were investigated by micro-indentation and dynamic mechanical thermal analysis (DMTA) respectively, to correlate the scratch behavior to the mechanical and structural properties of the clearcoats. The results revealed that incorporation of FOSS cages into clearcoats could effectively enhance the scratch resistance. This was attributed to the higher hardness and cross-linking density of the resulting nanocomposite coatings. The healing results also demonstrated that nanocomposites had a higher healing ability compared to the neat clearcoat. The higher healing of nanocomposites was explained by the physical H-bonding interactions formed in vicinity of POSS cages. The transparency measurements proved that these improvements were fulfilled without any negative effect on the optical quality of clearcoats.

2013 - Chemical and thermomechanical tailoring of the shape memory effect in poly(epsilon-caprolactone)-based systems [Articolo su rivista]
Messori, Massimo; DEGLI ESPOSTI, Micaela; Paderni, Katia; S., Pandini; S., Passera; T., Riccò; M., Toselli

The thermally activated shape memory response of polymeric materials results from a combination of the material molecular architecture with the thermal/deformational history, or ‘programming’. In this work, we investigate the shape memory response of systems based on poly (epsilon-caprolactone) (PCL) so as to explore the adoption of proper chemical and thermomechanical tailoring routes. Cross-linked semicrystalline PCL-based materials are prepared by different molecular architectures starting from linear, three- and four-arms star PCL functionalized with methacrylate end groups, allowing to tune the melting temperature, Tm, ranging between 36 and 55 °C. The materials’ ability to display the shape memory is investigated by the application of proper thermomechanical cycles on specimens deformed at two different temperatures (23 and 65 °C, i.e. below and above the Tm, respectively). The shape memory response is studied under dynamic thermal conditions in thermally activated recovery tests, to identify the typical transformation temperatures, and under isothermal conditions at given recovery temperatures, to monitor shape recovery as a function of time. All the specimens are capable of full recovery on specific thermal ranges influenced by both melting and deformation temperatures. Specimens deformed above Tm are able to recover the whole deformation in a very narrow temperature region close to Tm, while those deformed at room temperature display broader recovery processes, those onset at about 30 °C. Isothermal tests reveal that when the deformed material is subjected to a constant recovery temperature, the amount of recovered strain and the time required strongly depend on the particular combination of melting temperature, deformation temperature and recovery temperature.

2013 - Fracture toughness enhancement of UV-cured epoxy coatings containing Al2O3 nanoparticles [Articolo su rivista]
Sangermano, Marco; Naguib, Mohamed; Messori, Massimo

Commercially available alumina powder (-Al2O3 nanoparticles with 150nm diameter) is added up to 4 vol% into cycloaliphatic epoxy resins and cured using UV light. Chemical and physical investigations of these UV-cured, reinforced epoxy resin are carried out. The FTIR analysis indicates decreasing effect of these nanoparticles on the curing rate. The FESEM study for the fracture surface of reinforced epoxy resins revealed increase in the surface roughness that might be a sign of toughness enhancement. Also, an improvement in the scratch resistance was noticed for samples containing alumina filler.

2013 - Multifunctional antistatic and scratch resistant UV-cured acrylic coatings [Articolo su rivista]
Marco, Sangermano; David, Foix; Galder, Kortaberria; Messori, Massimo

Organic–inorganic antistatic hybrid acrylic coatings were prepared. Trialkoxy-silyl ammonium salt was added to the photocurable formulations in order to introduce an antistatic additive which could be covalently linked to the hybrid network through a co-condensation reaction involving the alkoxy groups. The influence of the antistatic additive on the radical photopolymerization reaction of the acrylic resin was evaluated by real time FTIR, keeping the inorganic precursor content constant at 20 phr and increasing the trialkoxy-silyl ammonium salt in the range between 5 and 15 phr. When the samples were cured under nitrogen atmosphere, a complete conversion of acrylic double bonds was achieved after 90 s of irradiation both for the acrylic resin and the formulations containing the ammonium salt. The scratch behavior of coatings was investigated by carrying out of progressive load scratch test. The penetration depth (Pd) and the residual depth patterns were investigated for all the hybrid films. A consistent improvement of penetration resistance by increasing alkoxy-ammonium salt content was noted in terms of Pd. Inorganic component and antistatic additives increase ε′ and σAC values of the hybrid coatings and decrease the resistivity ones, showing their efficiency for increasing antistatic properties of coatings, improved with respect to the pure acrylic resin.

2013 - Novel toughened automotive clearcoats modified by a polyester-amide hyperbranched polymer: structural and mechanical aspects [Articolo su rivista]
H., Yari; M., Mohseni; Z., Ranjbar; Messori, Massimo; M. R., Naimi Jamal

The present work attempts to study the mechanical properties and toughness behavior of a typical acrylic melamine clearcoat modified by a polyester-amide hyperbranched polymer (HBP). Formulations were such that 0, 5, 10, 25 and 50% (molar percent) of total acrylic hydroxyl groups were stoichiometrically substituted by those of HBP. Bulk and surface of the clearcoats were studied by various mechanical techniques including hardness, tensile, dynamic mechanical thermal analysis (DMTA), nano-indentation and scratch tests. In addition a scanning electron microscope (SEM) was utilized to observe the morphology of the fractured films. The bulk mechanical properties showed that a low loading (5 molar %) of HBP was sufficient to considerably increase the bulk hardness, cross-linking density and toughness. DMTA and SEM results proved the occurrence of a single-phase blend and that the shear deformation was the main toughening mechanism of HBP modified clearcoats. In general, it was revealed that the HBP not only could act as an excellent compatible toughening agent, but also maintained the clarity of the clearcoat and increased its scratch resistance.

2013 - One-way and two-way shape memory behaviour of semi-crystalline networks based on sol-gel cross-linked poly(ε-caprolactone) [Articolo su rivista]
S., Pandini; F., Baldi; Paderni, Katia; Messori, Massimo; M., Toselli; Pilati, Francesco; A., Gianoncelli; M., Brisotto; E., Bontempi; T., Riccò

In this work we have explored the shape memory capabilities of a novel type of covalently cross-linked semi-crystalline polymers, prepared by exploiting the mild solegel chemistry, starting from alkoxysilane-terminated poly(ε-caprolactone) (PCL), and using silica-based domains as cross-link points. By adopting PCL precursors with different molecular weights, semi-crystalline networks with well defined cross-link densities and with different crystallization and melting temperatures were obtained. Beside a satisfying one-way shape memory behaviour, the materials have displayed a significant two- way shape memory response, undergoing a reversible elongation-contraction process between two distinguished strain levels when subjected to a constant load and cyclically heated/cooled on a temperature region spanning from below the crystallization temperature to above the melting temperature. The applied load and the cross-link density are revealed as key-parameters to obtain tailored actuations. Concurrent wide-angle X-ray diffraction (WAXD) and DSC analyses allowed to ascribe the effect to a structural evolution process occurring during melting and crystallization.

2013 - Organic–Inorganic Hybrid Coatings with Enhanced Scratch Resistance Properties Obtained by the Sol–Gel Process [Capitolo/Saggio]
Messori, Massimo; Marco, Sangermano

State of the art of organic–inorganic hybrid coatings with enhanced scratch resistance properties obtained by the sol–gel process

2013 - Photo-cured epoxy networks functionalized with Fe3O4 generated by non-hydrolytic sol-gel process [Articolo su rivista]
M., Sangermano; P., Allia; P., Tiberto; G., Barrera; Bondioli, Federica; Florini, Nicola; Messori, Massimo

Magnetite nanoparticles were prepared by means of non hydrolytic sol-gel (NHSG) process in the presence of benzyl alcohol. The obtained magnetite suspensions were mixed with an aliphatic epoxy resin and the formulations were photopolymerized to achieve composite materials with magnetic properties. The prepared magnetite nanoparticles and epoxy composites were fully characterized in terms of their magnetic properties.

2013 - Preparation and characterization of EPDM rubber modified within situgenerated silica [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; Adriaan S., Luyt; Thabang H., Mokhothu; Messori, Massimo

This article is concerned with the preparation of a filled elastomer by means the nonconventional bottom-up approach to polymer composites, alternatively with the conventional mechanical compounding of preformed filler particles with rubber. EPDM rubber was modified with in situ generated silica particles prepared by means of a sol–gel process adopting a solution process. The used synthetic procedure permitted the preparation of highly filled rubbers (up to 40 wt % of silica) with silica particle dimensions ranging from 0.2 to 2 um. Equilibrium swelling and extraction tests indicated a hindering effect of the presence of in situ generated silica on the vulcanization process which reduced the cross linking degree of the rubber matrix. Both tensile tests and dynamic–mechanical analysis showed a significant improvement in the mechanical properties due to the presence of the reinforcing filler, with an enhancement more significant than that expected from a simple hydrodynamic reinforcing mechanism.

2012 - Gomma EPDM rinforzata con silice generata in-situ [Relazione in Atti di Convegno]
Morselli, Davide; Bondioli, Federica; Messori, Massimo

gomma EPDM è stata rinforzata generando silice in situ mediante tecnica sol-gel. Il processo in soluzione adottato ha permesso l’ottenimento di campioni a elevata quantità di filler (fino a un 30% in peso). Sia il test a trazione che il comportamento dinamico meccanico hanno dimostrato un netto miglioramento delle proprietà meccaniche dovuto alla presenza del filler rigido in grado di rinforzare la matrice gommosa. Dalle prove a trazione è stato trovato un modulo elastico iniziale significativamente incrementato se confrontato a quello teorico calcolato dall’equazione di Smallwood-Guth-Einstein considerando un semplice meccanismo di rinforzo idrodinamico.

2012 - Interrelation between preparation conditions, structure, and mechanical reinforcement in isoprene rubber filled with in situ generated silica [Articolo su rivista]
F., Bignotti; S., Borsacchi; R., de Santis; M., Geppi; Messori, Massimo; U. P., Sudhakaran

The sol–gel technique was used to reinforce isoprene rubber (IR) by generating silica in situ from tetraethoxysilane (TEOS). The aim of the research was to elucidate the effect of the preparation conditions on the structural and morphological characteristics of silica and the resulting mechanical reinforcement. The structure of the in situ generated silica was analyzed by 29Si high-resolution solid-state NMR spectroscopy, which evidenced a high condensation degree of TEOS that decreased with increasing the sol–gel reaction time. The silica dispersion became less homogeneous as the TEOS content and the reaction time were increased. The incorporation of a coupling agent (OTES, octyltriethoxysilane) in the reaction mixture promoted full conversion of TEOS. Lower particle size, better silica dispersion, and higher filler-matrix adhesion were noticed if the incorporation of OTES was delayed compared to TEOS. Uniaxial tensile tests evidenced that the tensile strength typically increased in the first 60 min of reaction and then leveled off. A similar behavior was observed for the high deformation stiffness, whereas at low deformations, the stiffness increased monotonically with the reaction time. In the vulcanizates with silica contents higher than 25 wt %, a drastic stiffness decrement was observed passing from low to high deformations. This reduction was ascribed to the disruption of the secondary filler network occurring in these materials when severely stretched.

2012 - Memoria di forma elettro-attivata di compositi polimerici contenenti nanocariche conduttive [Relazione in Atti di Convegno]
A., Pegoretti; G., Giusti; A., Dorigato; Messori, Massimo; Bondioli, Federica

Sono stati preparati e caratterizzati nanocompositi elettricamente conduttivi, al fine di creare un dispositivo a memoria di forma elettro-attivato. Come matrice polimerica è stata utilizzata una base epossidica, reticolata con un indurente amminico tal quale e nanocaricato con particelle di argento (Ag) generate in-situ. Per incrementare la conducibilità del materiale risultante, sono state inoltre aggiunte varie percentuali di nanoparticelle di carbon black (CB) e nanofibre di carbonio (NF). Le analisi termiche (DSC) mostrano come l’aggiunta di nanocariche carboniose porti ad un lieve abbassamento della Tg rispetto al materiale tal quale, mentre le osservazioni morfologiche (FESEM) hanno evidenziato come il carbon black (CB) tenda a creare degli agglomerati uniformemente dispersi nella matrice, con dimensioni crescenti all’aumentare del contenuto di carica. Sia il modulo elastico che le proprietà a snervamento diminuiscono con l’introduzione del CB, mentre le nanoparticelle di Ag garantiscono un interessante effetto irrigidente ed un incremento della resistenza flessionale. La presenza di CB contribuisce maggiormente all’abbassamento della conducibilità elettrica rispetto alle nanofibre di carbonio. E’ stato inoltre osservato un interessante abbassamento della resistività, dovuto all’effetto sinergico tra le nanocariche con diversa morfologia. L’introduzione di CB garantisce un rapido riscaldamento del campione per effetto Joule, mentre l’utilizzo di nanoparticelle di Ag assicura la stabilizzazione della temperatura per tempi di applicazione del voltaggio elevati. La valutazione del grado di recupero della forma su un dispositivo preparato a partire dalla composizione più interessante ha evidenziato un recupero completo della forma per tempi limitati (< 60 s) con una tensione di 220 V.

2012 - Multifunctional Luminescent Organic/ Inorganic Hybrid Films [Articolo su rivista]
Ignazio, Roppolo; Messori, Massimo; Sandrine, Perruchas; Thierry, Gacoin; Jean Pierre, Boilot; Marco, Sangermano

Transparent light-emitting hybrid materials are produced by UV curing of acrylic resins containing silica precursors and photoluminescent [Cu4I4L4] clusters. Acrylic double-bond conversion is followed by means of FT-IR spectroscopy, and optical measurements are performed on cured films showing a high transparency of the films up to a content of 30wt% TEOS and a bright luminescence with a maximum of emission centered at 565nm (yellow-orange). This study shows the possibility to obtain new advanced materials in which functional properties such as photoluminescence and scratch resistance are successfully conjugated in a hybrid film that maintains high transparency.

2012 - PMMA-titania nanocomposites: Properties and thermal degradation behaviour [Articolo su rivista]
T. E., Motaung; A. S., Luyt; Bondioli, Federica; Messori, Massimo; M. L., Saladino; A., Spinella; G., Nasillo; E., Caponetti

Titania nanoparticles were prepared using a sol-gel method and calcination at 200 and 600 C in order to obtain anatase and rutile phases, respectively. The obtained powders were used to prepare PMMA-titania nanocomposites by a melt compounding method. The effect of the crystalline phase and the amount of titania, in the range 1-5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of PMMA was investigated by means of X-ray diffractometry (XRD), transmission electron microscopy (TEM), 13C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy (13C{1H}CP-MAS NMR), including the measurement of proton spin-lattice relaxation time in the rotating frame (T1ρ(H)), in the laboratory frame (T1(H)) and cross polarization times (TCH), and dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and Fourier-transform infrared (FTIR) spectroscopy. Results showed that both types of titania were well dispersed in the polymeric matrix, whose structure remained amorphous. The two types of nanoparticles influenced the degradation of the polymer in different ways because of their different carbon content, particle size and crystal structures.

2012 - Photo-cured epoxy networks reinforced with TiO2 in-situ generated by means of non-hydrolytic sol-gel process [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; M., Sangermano; Messori, Massimo

Suspensions of titania nanoparticles in benzyl alcohol were synthesised from TiCl4 by means of non- hydrolytic sol-gel (NHSG) process. The stable suspensions were mixed with an aliphatic epoxy resin and subsequently photo-polymerised in the presence of a cationic photo-initiator to produce transparent composite films. The presence of titania didn’t influence significantly the polymerisation rate, while a progressive decrease in the maximum value of epoxy groups conversion was observed by increasing the titania content. Gel content analysis demonstrated that all organic species (benzyl alcohol and corresponding by-products) were covalently linked to the epoxy network, suggesting that both ‘active chain end’ and ‘activated monomer’ mechanisms were active during the propagation step in the cationic ring- opening polymerisation. The presence of titania increased significantly both glass transition temperature and modulus (in the rubbery region) confirming the reinforcing and stiffening effect due to both the presence of inorganic nanofillers and, most importantly, a higher cross-linking density of the composite material with respect to the pristine epoxy matrix. Nano-indentation and scratch tests also showed a systematic increase of hardness and scratch resistance by increasing the filler content.

2012 - Poly(methyl methacrylate)–TiO2 nanocomposites obtained by non-hydrolytic sol–gel synthesis: the innovative tert-butyl alcohol route [Articolo su rivista]
Morselli, Davide; Bondioli, Federica; M., Fiorini; Messori, Massimo

The present article concerns the preparation of poly(methyl methacrylate)/titania nanocomposites by a non-conventional bottom-up approach, as alternative to the conventional mechanical compounding of preformed filler particles. Poly(methyl methacrylate) (PMMA) was modi- fied with in situ generation of titania nanoparticles by means of the so-called non-hydrolytic sol–gel (NHSG) process in the presence of tert-butyl alcohol (tBuOH) as oxygen donor and polymer solvent. The results showed that the synthetic procedure used permitted the preparation of the highly filled PMMA (up to 20 phr of titania in anatase form) with titania actual content values very close to the nominal ones and with enhanced filler dispersion and homogeneous distribution within the polymeric matrix, avoiding the typical rheological problems related to distributive and dispersive mixing of conventional compounding methods. The presence of titania nanoparticles led to increases in glass transition temperature and E' modulus in the rubbery region for all the prepared samples with respect to the pristine PMMA. Finally, the nano-composites showed an interesting photo-catalytic activity towards organic molecules. The findings led us to conclude that the NHSG process was successfully employed to produce anatase titania in the presence of tBuOH and PMMA. The proposed process seems to offer a very promising method to produce polymer nanocomposites with good filler dispersion and homogeneous distribution and with interesting functional properties such as photo-catalytic activity.

2012 - Resine epossidiche rinforzate con titania generata in situ mediante processo dol-gel non idrolitico [Relazione in Atti di Convegno]
Morselli, Davide; Bondioli, Federica; M., Sangermano; Messori, Massimo

Sospensioni di nanoparticelle di titania in alcol benzilico sono state preparate mediante processo sol-gel non-idrolitico e miscelate a una resina epossidica alifatica. Le formulazioni ottenute sono poi state foto-polimerizzate in presenza di un foto-iniziatore cationico per produrre film nanocompositi. La presenza di titania non ha variato significativamente la velocità di foto-polimerizzazione, mentre è stata osservata una riduzione della conversione massima di gruppi epossido all'aumentare del contenuto di titania. Attraverso l'analisi del contenuto di gel è stato evidenziato che tutte le specie organiche presenti (alcol benzilico e relativi sottoprodotti) sono covalentemente legati al reticolo epossidico indicando che entrambi i meccanismi 'active chain end' e 'activated monomer' sono attivi nella fase di propagazione della polimerizzazione cationica per apertura di anello. La presenza di titania ha portato a significativi aumenti sia della temperatura di transizione vetrosa che del modulo e questo effetto di rinforzo è stato attribuito, oltre che all'atteso effetto idrodinamico legato alla presenza di particelle rigide, anche a una maggiore densità di reticolazione nel materiale composito rispetto alla resina epossidica pura.

2012 - Shape-memory polymer networks from sol–gel cross-linked alkoxysilane-terminated poly(e-caprolactone) [Articolo su rivista]
Paderni, Katia; S., Pandini; S., Passera; Pilati, Francesco; M., Toselli; Messori, Massimo

A novel type of covalently cross-linked semi- crystalline polymer with shape-memory and biocompatibility properties was prepared from alkoxysilane-terminated poly(e-caprolactone) (PCL) by sol–gel process that allowed the generation of silica-like cross-linking points. A fine tuning of the cross-linking density and thermal properties (melting temperature) of the materials was obtained by controlling the molecular weight of the PCL precursor (and thus the molecular structure of the resulting network) and the curing conditions. The shape-memory behaviour was investigated with bending tests. Recovery times of less than one second were observed in water depending on the temperature, and a linear correlation of the recovery time with cross-linking density and molecular weight of PCL network precursor was observed.

2012 - Surface Property Modification of Epoxy Coatings by Polydimethylsiloxanes [Articolo su rivista]
M., Sangermano; F., Sordo; Messori, Massimo

Surface properties of epoxy coatings are modified by PDMS additives in cationic UV curing of a cycloaliphatic epoxy resin. The cured films show a very high hydrophobicity that does not depend on PDMS concentration, indicating that a threshold is reached even at 0.3wt% additive. A slight increase of the water contactangle as a function of PDMS molecular weight is observed. The additive selectively modified the air-side of the film, while the glass-side retains the surface properties of the pure resin. This segregation phenomenon permits to obtain highly hydrophobic films with still good adhesion properties on polar substrates, which is an important advantage over common surface-modified resins.

2012 - Tailored One-Way and Two-Way Shape Memory Response of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications [Relazione in Atti di Convegno]
Pandini, Stefano; Passera, Simone; Riccò, Theonis; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Dassa, Luca; Cambiaghi, Danilo; Paderni, Katia; DEGLI ESPOSTI, Micaela; Toselli, Maurizio; Pilati, Francesco; Messori, Massimo

A series of crosslinked poly(epsilon-caprolactone) (PCL) materials were obtained starting from linear, three- and four-arm star PCL functionalized with methacrylate end-groups, allowing to tune the melting temperature (T-m) on a range between 36 and 55 degrees C. After deforming the specimens at 50% above T-m, the materials are seen to fully restore their original shape by heating them on a narrow region close to T-m; further, when the shape memory effect is triggered under fixed strain conditions, the materials are able to exert stress on a range between 0.2 and 7 MPa. The materials also display two-way shape memory features, reversibly moving between two shapes when cooled and heated under a fixed load. Finally, to investigate the application of the PCL materials as self-expandable stents, one-way shape memory experiments are currently carried out on tubular specimens.

2012 - Two-way reversible shape memory behaviour of crosslinked poly(ε-caprolactone) [Articolo su rivista]
S., Pandini; S., Passera; Messori, Massimo; Paderni, Katia; M., Toselli; A., Gianoncelli; E., Bontempi; T., Riccò

Polymers capable of reversible “two-way” shape memory behaviour are of great interest for applications where reversible actuation is demanded, and semicrystalline crosslinked systems have been indicated as an interesting solution towards this end. In this work we have explored the two-way shape memory response of semicrystalline poly(ε-caprolactone)-based polymer networks, prepared with various macromolecular architectures starting from linear, three- and four-arm star poly(ε-caprolactone) functionalized with methacrylate end-groups. All the materials have revealed two-way shape memory capabilities. The effect arises from an elongation process that takes place when the material is cooled under an applied load below the crystallization temperature, and that is completely reversed when heated again above melting temperature, in a manner that strongly depends on the applied load and on the material crosslink density. Two-dimensional XRD analysis, carried out on elongated specimens, shows that the elongation on cooling is accompanied by a change in the crystallinity orientation along the direction of stretch.

2011 - Enhancement of scratch-resistance properties of methacrylated UV-cured coatings [Articolo su rivista]
M., Sangermano; E., Gaspari; L., Vescovo; Messori, Massimo

Methacrylic based organic–inorganic hybrid coatings containing silica, titania or alumina domains, were generated in situ combining a UV-induced polymerization reaction with a sol–gel process of metal alkoxide precursors. While the presence of TEOS and ALP did not influence significantly the rate of curing and the final methacrylic double bond conversion, a certain effect is evident when TIP is added as inorganic precursor both on UV-curing rate and final double bond conversion. An increase of the rigidity of the cured coating was achieved in the presence of the inorganic fillers with an increase of Tg values by increasing the metal alkoxide content in the photocurable formulations. Scratch test showed a general increase of first and second critical load values for hybrid coatings together with an increase in the Persoz hardness values.

2011 - Epoxy resin modified with in situ generated metal oxides by means of sol–gel process [Articolo su rivista]
Bondioli, Federica; Darecchio, MARIA ELENA; Adrian S., Luyt; Messori, Massimo

Organic–inorganic hybrids were prepared with silica, zirconia, or titania in situ generated within epoxy resins based on bisphenol A diglycidyl ether and Jeffamine® by means of the aqueous sol–gel process. The morphology of the prepared hybrids varied from a particulate dispersed phase to a co-continuous morphology. Silica and zirconia filled epoxies were characterized by a significant increase in thermal stability, attributable to the high thermal stability of silica and zirconia phases. On the contrary, the introduction of titania induced a strong decrease in thermal stability of the epoxy/titania hybrids compared with the pure epoxy resin, attributable to metal-catalyzed oxidative decomposition mechanism in the polymer/titania composite. Hybrids were much more transparent than unfilled epoxy. The transmittance of silica- and titania-based hybrids showed a slight decrease by increasing the content of filler, while the transparency of zirconia-based hybrids was very high and almost constant independently by the nominal content of filler. The presence of in situ generated fillers significantly enhanced the scratch resistance of the epoxy resin as indicated by the marked increase of critical load for all the hybrids.

2011 - Flame retardant SBS-clay nanocomposites [Capitolo/Saggio]
Mauro Comes, Franchini; Messori, Massimo; Ori, Guido; Siligardi, Cristina

Polymer nanocomposites have revolutionized material performance, most notably in the plastcs, automotive, and aerospace industries. In this book leaders in the field outline the mechanism behind the generation of suitable polymer systems, pulling together recent research to provide a unified and up-to-date assessment of recent technological advances.

2011 - In Situ Synthesis of Rubber Nanocomposites [Capitolo/Saggio]
Messori, Massimo

The preparation and characterization of rubber based nanocomposites prepared by in situ generation of inorganic oxides by means of the hydrolytic sol– gel process are reviewed in the present chapter. The sol–gel approach has been applied to several rubber matrices to prepare reinforced vulcanized and unvul- canized rubbers. Several synthetic procedures are presented while the most investigated filler is silica obtained by hydrolysis and condensation of tetraeth- oxysilane. The effects of the different preparation conditions and of the filler content are generally discussed in terms of morphology (investigated by electron microscopy and small angle X-ray scattering) and mechanical properties (modulus, strength and extensibility). The mechanical properties of the in situ filled nano- composites are generally better than those of the corresponding materials prepared with the conventional mechanical mixing of preformed particulates and elasto- mers. This enhancement is generally attributed to a lower tendency to filler–filler aggregation due to a lower particle surface interaction resulting from the ‘bottom- up approach’ of the sol–gel process applied to the preparation of organic–inorganic hybrid materials.

2011 - Isoprene Rubber Filled with Silica Generated In Situ [Articolo su rivista]
Messori, Massimo; Maurizio, Fiorini

We modified synthetic isoprene rubber by means of the in situ generation of silica particles through the sol–gel process starting from tetraethoxysilane (TEOS) as an inorganic oxide precursor. Different reaction condi- tions were investigated with variations in the initial TEOS content, the reaction time of the sol–gel process, and the presence of a coupling/surfactant agent (octyltriethoxy- silane). Organic–inorganic hybrid materials with a silica content up to 70 phr were obtained with the complete con- version of TEOS to silica for a long enough sol–gel reac- tion time. A very homogeneous dispersion of silica particles was observed in all cases together with a very good adhesion between the filler and matrix. The size of the in situ generated silica was controlled by the appropri- ate addition of octyltriethoxysilane. Swelling and extrac- tion tests and dynamic mechanical analysis indicated that the vulcanization process of isoprene rubber was per- turbed by the sol–gel process; this led to a slight decrease in the crosslinking degree. However, a significant reinforc- ing effect due to the presence of silica particles was observed for all of the investigated samples.

2011 - Perfluoropolyether-based organic–inorganic coatings [Articolo su rivista]
Messori, Massimo; Fabbri, Paola; Pilati, Francesco; C., Tonelli; M., Toselli

In the present paper a comprehensive analysis on the preparation and characterization oforganic–inorganic hybrids containing perfluoropolyethers (PFPE) as organic component and silica (in situgenerated from tetraethoxysilane by means of the sol–gel process) as inorganic counterpart is reported.PFPE with different molecular weights and functionalities have been used in order to improve the miscibilitywith respect to other reactants and solvents comprising the final formulation of the coating. Inthis respect, PFPE oligomers have been used with or without chain extension with polycaprolactonesegments. The hybrids have been applied with different techniques onto glass substrates as functionalcoatings and the effects of different molecular structures, molecular weights and organic–inorganic ratioshave been thoroughly investigated in terms of surface properties (i.e. water and oil wettability and surfacesegregation of PFPE segments).

2011 - Poly(1,4-cyclohexylenedimethylene-1, 4-cyclohexanedicarboxylate): analysis of parameters affecting polymerization and cis-trans isomerization [Articolo su rivista]
M., Colonna; C., Berti; E., Binassi; A., Celli; M., Fiorini; P., Marchese; Messori, Massimo; D. J., Brunelle

Weatherable semicrystalline polyesters based on 1,4-cyclohexanedimethanol, 1,4-cyclohexanedicarboxylic acid (CHDA) or dimethyl 1,4-cyclohexane dicarboxylate (DMCD) can be prepared under normal melt-phase conditions, using titanium tetrabutoxide as catalyst. The effect of monomer ratio, reaction temperature and catalyst loading on the final polymer properties was studied. Under the proper polymerization conditions, poly(1,4-cyclohexylenedimethylene-1,4-cyclohexanedicarboxylate) polymers with high molecular weight can be obtained. During polymerization, isomerization can occur towards the thermodynamically stable cis-trans ratio of 34-66 mol%. Carboxylic acid end groups can catalyze the isomerization and therefore the polymerization is more critical starting from CHDA rather than DMCD. Moreover, temperature control becomes a key factor to avoid or to limit isomerization. The study of the isomerization of the different monomers permitted a better understanding of the isomerization and therefore of the polymerization process.

2011 - Poly(methyl methacrylate)-TiO2 nanocomposite obtained by non-hydrolytic sol–gel synthesis [Articolo su rivista]
Morselli, Davide; Messori, Massimo; Bondioli, Federica

Poly(methyl methacrylate) (PMMA)/titanium dioxide (TiO2) nanocomposites were prepared by means of in situ generation of TiO2 through a non-hydrolytic sol–gel process (NHSG), starting from titanium chloride, as titania precursor, benzyl alcohol, as oxygen donor, and commer- cial PMMA. TiO2 nanoparticles (average size of 30 nm) were obtained in the anatase and amorphous forms. The in situ generation led to a very homogeneous distribution of particulate fillers within the polymeric matrix avoiding the problems related to distributive and dispersive mixing of conventional compounding methods (top down approach). A slight increase of glass transition temperature was observed for all prepared composites with respect to the pristine PMMA. The NHSG process did not affect the molecular weight of the polymers indicating the absence of any degradation reaction for PMMA. The presence of titania in the anatase phase increases the photodegradation of the PMMA matrix due to UV irradiation.

2011 - Polycarbonate reinforced with silica nanoparticles [Articolo su rivista]
A. S., Luyt; Messori, Massimo; Fabbri, Paola; J. P., Mofokeng; Taurino, Rosa; Zanasi, Tania; Pilati, Francesco

Nanocomposites of polycarbonate (PC) reinforced with nanosized silica particles were prepared by a melt mixing technique in an internal mixer. Two kinds of commercial hydrophilic fumed silicas differing in their specific surface area were added in amounts up to 5% by volume, and their reinforcing action was compared to that of organically modified silica, loaded in the same amounts. Particle–matrix interactions were investigated by means of rheological and dynamic-mechanical thermal analysis, demonstrating the important role played by the organic modifi- cation in the interactions with the polymer matrix, and showing an optimal nano- particle loading around 2 vol%. The scratch resistance of the nanocomposites obtained from hydrophilic silicas was investigated, and a remarkable enhancement in the indenter’s penetration resistance was observed for all the compositions with respect to pristine PC. The same behaviour was observed for the Shore D hardness and for the impact resistance of the nanocomposites that also significantly improved with the maximum load shifting from a minimum value of 521 N for pristine PC up to values grater than 1330 N for the nanocomposites, demonstrating the activation of effective mechanisms of energy dissipation due to the presence of the nanofillers.

2011 - Synthesis and Phase-Separation Behavior of a,x-Difunctionalized Diblock Copolymers [Articolo su rivista]
S., Werner; D., Pospiech; D., Jehnichen; K., Eckstein; H., Komber; P., Friedel; A., Janke; F., Näther; U., Reuter; B., Voit; Taurino, Rosa; Messori, Massimo

A series of diblock copolymers of n-pentyl methacrylate and methyl methacrylate (PPMA/PMMA BCP) with one or two terminal functional groups was prepared by sequential anionic polymerization of PMA and MMA using an allyl-functionalized initiator and/or and end-capping with allyl bromide. Allyl functional groups were successfully converted into OH groups by hydroboration. The morphology in bulk was examined by temperature-dependent small-angle X-ray measurements (T-SAXS) and transmission electron microscopy (TEM) showing that functional groups induced a weak change in d-spacings L-0 as well as in the thermal expansion behavior. T-SAXS proved that the lamellar morphologies were stable over multiple heating cooling cycles without order-disorder transition (ODT) until 300 degrees C. While non-functionalized BCP formed parallel lamellae morphologies, additional OH-termination at the PMMA block forced in very thin films (ratio between film thickness and lamellar d-spacing below 1) the generation of perpendicular lamellae morphology through the whole film thickness, as shown by Grazing-incidence small-angle X-ray scattering experiments (GISAXS) measurements. Functionalized BCP were successfully used in thin films as templates for silica nanoparticles in an in-situ sol-gel process.

2010 - Improving Epoxy Adhesives with Zirconia Nanoparticles [Articolo su rivista]
A., Dorigato; A., Pegoretti; Bondioli, Federica; Messori, Massimo

Zirconia nanoparticles were synthesized by a sol–gel route and dispersed into an epoxy base for struc- tural adhesives. Nanoparticles were used as-synthesized or after calcination. Moreover, the effect of silane functionalization was also investigated. According to preliminary tensile mechanical tests on bulk nanocom- posite samples, calcined and untreated zirconia nanoparticles were selected for the preparation of adhesives with various filler contents.The glass transition temperature increased up to a filler content of 1 vol% and then decreased, probably due to the concurrent and contrasting effects of chain blocking and reduction of the crosslinking degree. Also tensile modulus, stress at break and fracture toughness of bulk adhesives samples were positively affected by the presence of an optimal amount of zirconia nanoparticles.Mechanical tests on single lap aluminium bonded joints indicated that zirconia nanoparticles led to rele- vant enhancements of the shear strength of the joints. In particular, the shear strength increased by about 60% for an optimal filler content of 1 vol%, and an adhesive failure mechanism was evidenced for all the tested specimens. Concurrently, a significant decrease of the equilibrium contact angle with water was observed for adhesives containing zirconia nanoparticles. It can therefore be concluded that the addition of zirconia nanoparticles can effectively improve epoxy adhesives, both by increasing their mechanical properties and by enhancing the interfacial wettability with an aluminium substrate.

2010 - Porous scaffolds of polycaprolactone reinforced with in situ generated hydroxyapatite for bone tissue engineering [Articolo su rivista]
Fabbri, Paola; Bondioli, Federica; Messori, Massimo; C., Bartoli; D., Dinucci; F., Chiellini

Polycaprolactone/hydroxyapatite (PCL/HA) composites were prepared by in situ generation of HA in the polymer solution starting from the precursors calcium nitrate tetrahydrate and ammonium dihydrogen phosphate via sol–gel process. Highly interconnected porosity was achieved by means of the salt-leaching technique using a mixture of sodium chloride and sodium bicarbonate as porogens. Structure and morphology of the PCL/HA composites were investigated by scanning electron microscopy, and mechanical properties were determined by means of tensile and compression tests. The possibility to employ the developed composites as scaffolds for bone tissue regeneration was assessed by cytotoxicity test of the PCL/HA composites extracts and cell adhesion and pro- liferation in vitro studies.

2010 - Scratch Resistance Enhancement of Polymer Coatings [Articolo su rivista]
M., Sangermano; Messori, Massimo

This review presents the state of the art regarding the improvement of scratch resistance of polymeric coatings. In particular, our attention is focused on the effect of inorganic nano- metric fillers on the scratch resistance of organic coatings. Two main strategies are described for the achievement of such nanostructured hybrid organic/inorganic coatings: either a top- down or a bottom-up approach.

2010 - UV-cured epoxy coatings modified with perfluoropolyether-based materials [Articolo su rivista]
M., Sangermano; Messori, Massimo; A., Rizzoli; S., Grassini

Hydroxy terminated PFPE were chain extended with short PCL segments in order to enhance the com- patibility towards the epoxy resin. The obtained PFPE–PCL block copolymers were used as additives to modify toughness of a UV curable bisphenol-A-based epoxy coating. A certain degree of phase separation was achieved during UV curing. The morphology of the obtained cured materials depends on the poly- caprolactone PCL length. The perfluoropolyether PFPE additive, without any PCL segment (additive TX), clearly showed a biphasic morphology with separated domains within 50–100 um. By increasing the PCL segment it was not identified any second distinct phase. It was shown that the addition of TX additive can generate a strong phase separation and this allowed to achieve an improvement of the toughness properties of the cured samples without affecting the thermo-mechanical properties.

2010 - Verniciatura di substrati plastici [Capitolo/Saggio]
Messori, Massimo

Atti del XXXI Convegno Scuola AIM Mario Farina su “Rivestimenti polimerici - Materiali, tecnologie e proprietà” - 17-20 Maggio 2010, Gargnano (BS)

2009 - Enhancing the scratch resistance of polycarbonate with poly(ethylene oxide)-silica hybrid coatings [Articolo su rivista]
Fabbri, Paola; Messori, Massimo; M., Toselli; Veronesi, Paolo; J., Rocha; Pilati, Francesco

Scratch-resistant coatings for bisphenol-A polycarbonate sheets were obtained by the sol–gel synthesis of an organic–inorganic hybrid system based on poly(ethylene oxide) and silica. The organic–inorganic hybrids were thermally cured into hard transparent coatings by using conventional and microwave (MW) ovens. Both techniques proved to be equally efficient in promoting the system’s crosslinking, as evaluated by 29Si MAS-NMR. The MW-assisted curing, however, was much faster. Photoelasticity analysis showed that MW-assisted curing causes localized overheating of the samples, inducing a state of residual plane stresses that bring about dimensional instability of the coated material. Instrumented scratch tests for the coated samples revealed an increase of 1 order of magnitude in the minimal load at which a scratch track appears on the sample surface. However, the friction coefficient values for samples with thermally cured coatings were lower than those produced by MW-assisted curing.

2009 - Improving the creep stability of high-density polyethylene with acicular titania nanoparticles [Articolo su rivista]
Bondioli, Federica; A., Dorigato; Fabbri, Paola; Messori, Massimo; A., Pegoretti

Acicular titania nanoparticles with average dimensions of 15 X 60 nm2 were produced by hydrothermal crystallization of TiOCl2. Titania particles were surface- functionalized with octadecylsilane to obtain an organophilic surface. High-density polyethylene (HDPE) nanocomposites were prepared by melt compounding with 2, 3, and 5 vol % concentrations of untreated and surface-functionalized titania nanoparticles. Quasi-static mechanical tensile tests evidenced slight increments of both the elastic modulus and stress at yield, which were accompanied by a marked reduction of the strain at break at high filler contents. The introduction of titania nanoparticles induced a substantial reduction of the creep compliance of the HDPE matrix and of its creep rate, especially at long loading times. Untreated titania nanoparticles were more effective in reducing the creep compliance than the functionalized ones.

2009 - Modification of isoprene rubber by in situ silica generation [Articolo su rivista]
Messori, Massimo; F., Bignotti; R., De Santis; Taurino, Rosa

BACKGROUND: The reinforcement of elastomers by the addition of fillers is one of the most important aspects in rubber science and technology. In order to optimise the filler – polymer interface, innovative in situ generation of silica within isoprene rubber was carried out by means of a bottom-up approach through a sol – gel process starting from tetraethoxysilane as silica precursor. The main aim was the study of the effect of the silica concentration and of the presence of coupling agent on the morphology and the dynamic mechanical behaviour of the composites.RESULTS: The in situ generated silica particles were homogeneously dispersed in the vulcanised rubber with dimensions from a few nanometres to the submicrometre scale. In the presence of coupling agent a good polymer – filler adhesion was observed. The dynamic mechanical behaviour was nonlinear for silica contents higher than 20 wt%. In this range of compositions silica exerted a marked reinforcement on the low-amplitude storage modulus, which is related to the silica content according to the Huber–Vilgis model.CONCLUSION: Isoprene rubber can be effectively reinforced by the in situ generation of silica for silica contents higher than 20 wt%, and the interaction at the silica – rubber interface can be optimised by using suitable coupling agents.

2009 - Organic–Inorganic Hybrid Coatings for the Modification of Barrier Properties of Poly(lactic acid) Films for Food Packaging Applications [Articolo su rivista]
Iotti, Marco; Fabbri, Paola; Messori, Massimo; Pilati, Francesco; Fava, Patrizia

Organic–inorganic hybrid coatings based on poly(e-caprolactone), poly(ethylene oxide) or poly(lactic acid) as organic phase and silica from tetraethoxysilane as inorganic phase were prepared by the sol–gel approach. Coatings were applied onto poly(lactic acid) films for food packaging in order to improve its barrier properties towards oxygen and water vapour. All the prepared coatings were dense, homogeneous layers characterized by a good adhesion to the substrate. The permeance of the coating layers resulted one order of magnitude lower than that of the uncoated poly(lactic acid) (PLA) film. The hydrophilic character of the coating did not permit to gain a significant decrease in the water vapour permeance. The perfect visual transparency of the coatings allows their application without worsening of the esthetical properties of the sub- strate PLA film.

2009 - Scratch resistant tough nanocomposite epoxy coatings based on hyperbranched polyesters [Articolo su rivista]
M., Sangermano; Messori, Massimo; M., Martin Galleco; G., Rizza; B., Voit

Advanced multifunctional coatings were prepared by UV curing of epoxy based formulations containing hyperbranched polymers (HBP) and an epoxy functionalized alkoxysilane additive. The addition of HBP to the UV curable epoxy resin induced an important flexibilization of the glassy epoxy network with an increase in toughness of the cured polymeric coatings. Adding the functionalized alkoxysilane into the UV curable formulations, as inorganic precursor of silica phase, an improvement on surface hardness was obtained without strongly affecting the flexibilization and the toughness achieved by the addition of the HBP additive. The increase on surface hardness was accompanied with an increase in scratch resistance and modulus. Advanced scratch resistant and tough nanocomposite epoxy coatings were obtained by properly selecting the components of the formulation.

2008 - Bentonite-based organoclays as innovative flame retardants agents for SBS copolymer [Articolo su rivista]
M., Comes Franchini; FABBRI, Paola; A., Frache; ORI, GUIDO; MESSORI, Massimo; SILIGARDI, Cristina; A., Ricci

Two organophilic bentonites, based on nitrogen-containing compounds, have been synthesised viaion exchange starting from pristine bentonite with octadecyltrimethylammonium bromide (OTAB)and with synthetic melamine-derived N2,N4-dihexadecyl-1,3,5-triazine-2,4,6-triamine (DEDMEL).The chemical and morphological characterization of the organoclays was based on XRD, TEM,Laser Granulometry, X-Ray Fluorescence and CEC capacity. Copoly(styrene-butadiene-styrene)-nanocomposites (SBS-nanocomposites) were obtained by intercalation of the SBS-copolymer intothese new organoclays by melt intercalation method. XRD and TEM analysis of the organoclaysand of the micro/nano-composites obtained are presented. The effect of the organoclays on theSBS-nanocomposite’s flammability properties was investigated using cone calorimeter. An encouragingdecrease of 20% in the peak heat released rate (PHRR) has been obtained confirming theimportant role of melamine’s based skeleton and its derived organoclays to act as effective fireretardants and for the improvement of this important functional property in SBS copolymers.

2008 - Epoxy resins modified with perfluoropolyethers: toughening and reduction of liquid absorption [Articolo su rivista]
Messori, Massimo; Pilati, Francesco; Fabbri, Paola; M., Toselli


2008 - Facile preparation of superhydrophobic coatings by sol–gel processes [Articolo su rivista]
R., Taurino; FABBRI, Elena; MESSORI, Massimo; PILATI, Francesco; D., Pospiech; A., Synytska

Different organic/inorganic compositions and deposition methods were used to prepare superhydrophobic surfaces using metal alkoxides and the sol–gel process. Both surface roughness and composition had to be adjusted in order to obtain very high contact angles and low contact angle hysteresis as a necessary requirement for superhydrophobicity. Multilayer samples with a fluorinated organic–inorganic top layer showed water contact angles of about 157° with low hysteresis (2°). Water drops rolled easily off their surface at a tilt angle as low as 4°.

2008 - High-density polyethylene reinforced with submicron titania particles [Articolo su rivista]
Bondioli, F.; Dorigato, A.; Fabbri, P.; Messori, M.; Pegoretti, A.

Submicron titania particles were prepared by means of two different synthetic procedures in order to obtain different particle size (diameter ranging from 20 to 350 nm), shapes, and morphologies (amorphous or crystalline). Titania particles were surface modified with octadecylsilane in order to improve their compatibility with respect to polymeric matrices. High-density polyethylene (HDPE)-titania composites were prepared by melt blending by using an internal mixer. The obtained composites were mechanically characterized in quasi static and creep tensile conditions. The presence of submicron titania particles (1 %vol) led to a significant increase of elastic modulus (20-25%) with respect to the unreinforced HDPE together with a slight increase of yield stress and a decrease of ultimate elongation. An interesting reduction for both elastic and viscoelastic creep compliance components was also evidenced. © 2008 Society of Plastics Engineers.

2008 - High-density polyethylene reinforced with titania nanoparticles [Articolo su rivista]
Bondioli, Federica; Dorigato, A; Fabbri, Paola; Messori, Massimo; Pegoretti, A.

Titania nanoparticles were prepared by means of two different synthetic procedures in order to obtain different particle size (diameter ranging from 20 nm to 350 nm), shapes and morphologies (amorphous or crystalline). Titania nanoparticles were surface modified with octadecylsilane in order to improve their compatibility with respect to polymeric matrices. High density polyethylene (HDPE) - titania nanocomposites were prepared by melt blending by using an internal mixer. The obtained nanocomposites were mechanically characterized and quasi static and creep tensile conditions. The presence of titania nanoparticles (1%vol) led to a significant increase of elastic modulus (20-25%) together with a slight increase of yield stress and a decrease of ultimate elongation. An interesting reduction of for both elastic and viscoelastic creep compliance components was also evidenced.

2008 - Hydrophobic and Oleophobic Coatings Based on Perfluoropolyether/Silica Hybrids by the Sol-Gel Method [Articolo su rivista]
Fabbri, Paola; Messori, Massimo; Pilati, Francesco; R., Taurino; C., Tonelli; M., Toselli

Glass substrates were spin-coated with a perfluoropolyether oligomer based organic-inorganic hybrid material, and prepared by the sol-gel process. Contact angle analysis and atomic force microscopic analysis were carried out to characterize the surface of the prepared coatings. All systems exhibited strong hydrophobic and oleopophobic characteristics. The wettability behavior was found to be almost independent of both molecular weight and functionality of the fluorinated oligomer. The low values obtained for the contact angle and surface tension indicate that surface segregation of perfluoropolyether segments is likely to take place within the network. On the basis of these results and the high quality of the obtained coatings, these materials could be used as functional coatings to impart water and oleo-repellent characteristics to glasses and other similar substrates.

2008 - Improvement of the surface properties of polycarbonate by organic-inorganic hybrid coatings [Articolo su rivista]
Fabbri, Paola; Leonelli, Cristina; Messori, Massimo; Pilati, Francesco; Toselli, M; Veronesi, Paolo; MORLAT THERIAS, S; Rivaton, A; Gardette, J. L.

Organic-inorganic hybrids (ceramers) were prepared through the sol-gel process with opportune alkoxysilane-terminated polymer chains as the organic phase and tetraethoxysilane as the inorganic network precursor. The consolidation process, used to reach a high degree of crosslinking between the two phases, was carried out with either conventional oven heating or microwave irradiation. High conversion degrees were obtained with both treatments even when microwave postcuring turned out to be much faster than conventional heating (5-10 s vs 40 min). Scratch-test and photooxidation investigations showed a significant improvement in scratch, yellowing, and photodegradation resistance for coated polycarbonate.

2008 - Monitoring of the sol-gel synthesis of organic-inorganic hybrids by FTIR transmission, FTIR/ATR, NIR and Raman spectroscopy [Relazione in Atti di Convegno]
D., Fischer; D., Pospiech; U., Scheler; R., Navarro; Messori, Massimo; Fabbri, Paola

The sol-gel synthesis of org.-inorg. hybrids based on triethoxysilaneterminated poly(ethylene oxide) and tetraethylorthosilicate was monitored in-situ using three spectroscopic methods (FTIR/ATR, Raman, NIR). These spectroscopic methods allow in-situ monitoring of the evolution of hybrid materials starting from the modification of the polymer and the early steps of hydrolysis up to the network formation. By application of 29Si solid-state NMR spectroscopy the assignment and quantification of the Raman bands to different end groups and different crosslinking states was made. The sol-gel reaction was also followed by in-line NIR spectroscopy. A multivariate data anal. was accomplished to obtain a conversion-time curve. Furthermore, we investigated spin-coated films on wafers using FTIR transmission spectroscopy.

Fabbri, Paola; Messori, Massimo; Pilati, Francesco; Rovati, Luigi

In questo lavoro è stata studiata la possibilità di preparare mediante tecnica sol-gel un sensore per misure di pH applicabile in punta di fibra ottica, che abbia come eventuali applicazioni l’utilizzo in pH-metria esofagea per monitorare i livelli di pH nell’esofago in pazienti affetti da reflusso gatroesofageo, il monitoraggio dei livelli di acidità o di basicità dei vapori industriali, di acque reflue, ecc. Si tratta di un sensore micro-invasivo che, grazie alla miniaturizzazione offerta dalla fibra ottica, consente di effettuare un monitoraggio continuativo del pH anche in situazioni complesse come la misura clinica a livello esofageo.

2008 - Scratch resistance of nano-silica reinforced acrylic coatings [Articolo su rivista]
E., Amerio; Fabbri, Paola; G., Malucelli; Messori, Massimo; M., Sangermano; R., Taurino

Organic–inorganic hybrid coatings were obtained by a dual-curing process combining the sol–gel reaction with the UV-induced polymerization technique by starting from bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA, as organic network former), methacryloyloxypropyltrimethoxysilane (MEMO, as coupling agent) and tetraethoxysilane (TEOS, as inorganic silica network precursor). For comparison, TEOS was also substituted with preformed silica nanoparticles. Scratch test was carried out in order to study the scratch resistance of that silica reinforced acrylic resins. Excellent scratch resistant coatings were obtained by UV and sol–gel dual curing process. On the contrary, coatings with very poor scratch resistance were obtained by dispersing preformed nano-silica into the acrylic resin indicating the key role played by the morphology of the inorganic filler and its interaction with the organic matrix.

2008 - UV Curing of Organic-Inorganic Hybrid Coatings Containing Polyhedral Oligomeric Silsesquioxane Blocks [Articolo su rivista]
Ezio, Amerio; Marco, Sangermano; Giovanna, Colucci; Giulio, Malucelli; Messori, Massimo; Rosa, Taurino; Fabbri, Paola

technique with a methacrylic oligomer and multifunctional methacrylic polyhedral oligomeric silsesquioxane blocks (POSS®). The results obtained from the polyhedral compounds were compared with those of a disordered framework obtained by the condensation of a silica precursor (MEMO). The inorganic domains generated during synthesis created constraints in movement of polymer segments, which reflected in an increase in Tg of the hybrid nanocomposite coatings. The films were transparent. The random structure obtained by the condensation of the MEMO showed a stronger effect on Tg than that observed by introducing POSS®. The effect of inorganic domains reflected on thermal stability, surface hardness and mechanical properties of the hybrid nano-composite coatings.

2008 - Use of single-wall carbon nanotubes as reinforcing filler in UV curable epoxy system [Articolo su rivista]
M., Sangermano; E., Borella; A., Priola; Messori, Massimo; R., Taurino; P., Pötschke

CNT were dispersed in an epoxy matrix and cured by means of UV light. An increase on elastic modulus and Tg values was measured by DMTA anal. and attributed to the constraint effect of CNT on polymer chain mobility. Excellent scratch resistant coatings characterized by high crit. load, small cracks and high recovery were obtained in the presence of a very low CNT content (0.025 wt.-%). TEM anal. showed some isolated CNT and some cluster agglomerations of size of about 250 nm. It was shown that it was possible to decrease the surface resistivity of the cured samples by three orders of magnitude in the presence of 0.1 wt.-% of SWCNT content.

2008 - Vinyl Ester Resins modified with Perfluoropolyethers [Articolo su rivista]
Messori, Massimo; Pilati, Francesco; M., Toselli; L., Mascia; C., Tonelli

Hydroxy-terminated Perfluoropolyether (PFPE) was modified by copolymerisation with caprolactone or by addition of carboxylic or methacrylic terminal groups to increase the miscibility towards Vinyl Ester Resins (VERs). Fluorinated oligomers were employed as additives for a commercial VER. Depending on both molecular structure and curing conditions, different morphologies were obtained, which in turn influence the final properties of the cured resin. Generally, a significant increase in toughness was observed as is indicated by the stress intensity factor. A marked decrease in water diffusion coefficient was obtained, thanks to the hydrophobic character of PFPE.

2007 - Applicazioni di sistemi ibridi da sol–gel [Capitolo/Saggio]
Messori, Massimo

Atti del XXVIII Convegno Scuola AIM Mario Farina su “Materiali polimerici ibridi e nanostrutturati” – 30 Aprile – 4 Maggio 2007, Gargnano (BS)

2007 - Design of surface properties of PET films: effect of fluorinated block copolymers [Articolo su rivista]
PILATI, Francesco; M., Montecchi; FABBRI, Paola; A., Synytska; MESSORI, Massimo; M., Toselli; K., Grundke; D., Pospiech

AbstractThis paper demonstrates that the addition of fluorinated block copolymers to PET solutions can be used to prepare PET films with controlled surface morphology, porosity and chemical composition, by exploiting the phenomenon known as breath figures (BF) formation during a spin-coating procedure. Surface features, such as number, depth and diameter of pores and chemical composition, can be tuned by varying the experimental conditions: relative humidity, solution composition and amount of the fluorinated block copolymer added to the PET solutions (in the range of 0.5–10 wt% with respect to PET). BF patterns are more evident at relatively high concentrations of PET (3 wt%) and content of fluorinated block copolymer (10 wt% with respect to PET) in the solution. According to the obtained results, the fluorinated block copolymer seems to play a role in different steps of the mechanism of BF formation. XPS measurements showed a surface composition much richer in fluorinated segments than expected from bulk composition. The combined surface roughness and surface segregation of fluorinated segments have only a limited effect on the macroscopic wettability of the surfaces.

2007 - Engineering plastics [Capitolo/Saggio]
Pilati, Francesco; Messori, Massimo; Fabbri, Paola; Toselli, M.

Volume II - Refining and petrochemicals - Chapter 12.6

2007 - Sol–gel derived hybrid coatings for the improvement of scratch resistance of polyethylene [Articolo su rivista]
M., Toselli; M., Marini; Fabbri, Paola; Messori, Massimo; Pilati, Francesco

Organic–inorganic hybrid materials were prepared through the sol–gel approach starting from tetraethoxysilane (TEOS), as silica precursor, and triethoxysilane terminated polymers; before gelling the solutions were applied to polyethylene (PE) films and slabs by spin-coating, without any previous surface pre-treatment of the substrate, and finally the coatings were thermally cured at 60 °C for 24 h. Among the various polymers used to prepare the coatings, only polyethylene-b-poly(ethylene glycol) copolymers gave good results in terms of adhesion to the PE substrates, and hybrid coatings with different organic–inorganic ratios were prepared. As suggested by visual inspection and SEM investigation, and confirmed by the critical loads derived from scratch tests, a good adhesion of the coating to the PE substrates was obtained, probably due to the presence of PE segments in the organic phase of the coating. Transparency as well as SEM and DSC data were in agreement with the formation of a nanostructured hybrid coating, with a high level of interpenetration between organic and inorganic domains. It was also observed that these hybrid coatings are able to improve significantly the scratch resistance and slightly increase the wettability with respect to uncoated PE. This approach to the surface-properties modification of PE appears as a simple and convenient method for the functionalization of PE substrates.

2006 - Cohesive and adhesive properties of polycaprolactone/silica hybrid coatings on poly(methyl methacrylate) substrates [Articolo su rivista]
Fabbri, Paola; B., Singh; Y., Leterrier; J. A. E., Manson; Messori, Massimo; Pilati, Francesco

Organic-inorganic hybrid materials were prepared using the sol-gel process in order to improve the scratch resistance of poly(methyl methacrylate) (PMMA) substrates. Sol-gel solutions based on tetraethoxysilane and alpha,omega-triethoxysilane terminated polycaprolactone with two different organic/inorganic weight ratios (5/5 and 7/3) were applied and cured on the substrate. The final coatings consisted of interconnected nanodomains of silica and polycaprolactone, which increased in size and resulted into microdomains when the content of organic phase increased. The surface energies of coated and uncoated PMMA, and the cohesive and adhesive properties of the hybrid coatings were examined using contact angle measurements, and fragmentation tests, respectively. The surface energy of the hybrid coatings and their work of adhesion to the PMMA substrate were found to be similar, with a higher polar contribution at increasing silica content. In contrast, the strain to failure, cohesive strength, toughness and adhesion to PMMA of the coating with a 5/5 organic/inorganic ratio were considerably higher, compared to the coating with a 7/3 organic/inorganic ratio. These results demonstrate that the adhesion strength is the result of a series of complex phenomena that probably involves diffusion of reactants in PMMA and their crosslinking, as suggested by electron energy loss spectroscopy analyses, other than effects deriving from residual stresses and from the morphology produced during the formation of the coating.

2006 - Electrical Behavior of PET Films Coated with Nanostructured Organic–Inorganic Hybrids [Articolo su rivista]
A., Saccani; M., Toselli; Messori, Massimo; Fabbri, Paola; Pilati, Francesco

Hybrid coatings, based on poly(ethylene oxide) (PEO) or polycaprolactone (PCL) and silica (SiO2), at different organic-inorganic compositions have been used to coat PET films employed in the electric industry to produce capacitors. The overall electrical behavior of the coated films has been investigated. The electrical strength of the coated films increases up to 10-15% of the uncoated ones regardless of polymer type (PEO/PCL) and amount of inorganic phase, as far as the thickness of the coating is below 5 μm. A systematic increase of surface electrical conductivity is found in all coated samples which however still behave as insulators. Permittivity and loss factor also increase particularly at low frequencies (< 10 Hz) on account of the presence of ions deriving from the sol-gel process and on the presence of interfacial polarization probably related to the coatings nanostructurated morphology which leads to phase separation.

2006 - Perfluoropolyether-based organic-inorganic hybrid coatings [Articolo su rivista]
Fabbri, Paola; Messori, Massimo; Montecchi, Monica; Nannarone, Stefano; Pasquali, Luca; Pilati, Francesco; C., Tonelli; M., Toselli

Perfluoropolyether-based organic-inorganic hybrids were prepared by sol-gel process and applied as functional coatings onto glass substrates. Contact angle analysis and X-ray photoemission spectroscopy were carried out in order to characterize the surface of the prepared coatings. A strong hydrophobic and lipophobic character was observed for all tested compositions. The wettability behaviour was found to be dependent on both the coating technique and the reaction time of the sol-gel reaction. A strong surface segregation of perfluoropolyether segments was noted for all the prepared samples as evidenced by XPS analysis. On the basis of the obtained results, these materials could be used as functional coatings to prepare water and oil repellent glasses or other substrates.

2006 - Preparation and characterization of epoxy resins filled with submicron spherical zirconia particles [Articolo su rivista]
Bondioli, Federica; Cannillo, Valeria; Fabbri, Elena; Messori, Massimo

Submicron spherical zirconia particles were synthesized and used as a reinforcement for epoxy resins. In fact, recent developments indicate that a significant improvement in the thermoset polymer performance may be obtained by using submicron inorganic filler. In this paper, different composites with weight fraction of the filler in the range 1-5% were prepared and characterized in terms of mechanical properties. A numerical model suitable for the description of such materials was set up and employed to estimate the properties as functions of the reinforcement content.

2006 - Surface properties of fluorinated hybrid coatings [Articolo su rivista]
Fabbri, Paola; Messori, Massimo; Montecchi, Monica; Pilati, Francesco; Taurino, Rosa; C., Tonelli; M., Toselli

A commercial perfluoropolyether containing alkoxysilane functionalities was employed to prepare organic-inorganic hybrid coatings by using the sol-gel process in the presence of tetraethoxysilane. Contact angle analysis revealed a strong hydrophobic and oleophobic character of the coatings almost independently from the molecular weight of the starting fluorinated oligomer. Surface tension values were in the range of 14-16 mN/m, suggesting a preferential segregation of fluorinated segments onto the surface of the coating. Atomic force microscopy showed the presence very smooth surfaces permitting to neglect the contribution of the surface roughness to wettability. Friction coefficient values were markedly lower with respect to the value of uncoated glass substrate.

2006 - Thiodiethylene glycol based polyesters: synthesis and thermal characterization [Articolo su rivista]
N., Lotti; L., Finelli; Messori, Massimo; A., Munari

Poly(thiodiethylene terephthalate) (PSDET), poly(thiodiethylene adipate) (PSDEA), poly( diethylene terephthalate) (PDET) and poly(diethylene adipate) (PDEA) for comparison were synthsized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermo gravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the sulfur-containing polyesters. At room temperature they appeared as semicrystalline materials, except PDEA, which was an oil; the effect of substitution of ether oxygen atoms with sulfur ones was a lowering in the T-g value, an increment of melting temperature and an increase of crystallization rate. The results were explained as due to the presence of flexible C-S-C bonds in the polymeric chain.

2005 - Epoxy-silica nanocomposites: Preparation, experimental characterization and modeling [Articolo su rivista]
Bondioli, Federica; Cannillo, Valeria; Fabbri, Elena; Messori, Massimo

Silica nanoparticles having different sizes were obtained by the sol-gel process and characterized. The prepared nanoparticles were subsequently used as reinforcing fillers to prepare epoxy-based composites with a silica content ranging from I to 5 wt %. SEM analysis and tensile tests carried out on the silica-epoxy nanocomposites indicated the absence of particle aggregation and a reinforcing effect in terms of increased elastic modulus. Mechanical properties were also modeled by using a finite element code able to construct a numerical model from a microstructural image of the material. A more reliable model was prepared by considering the presence of an interphase layer surrounding the particles with intermediate elastic properties between the epoxy and the inclusions and a characteristic size proportional to the particle radius.

2005 - Non-Conventional Curing of Organic-Inorganic Hybrids [Articolo su rivista]
Leonelli, Cristina; Messori, Massimo; Pilati, Francesco; Veronesi, Paolo

Infrared and microwave curing of organic-inorganic hybrid materials was studied, in order to achieve the maximum conversion without detrimental effects due to the overheating or to the long-time permanence at high temperature. Partially cured poly(ethylene oxide)/silica hybrids were prepared by hydrolysis and subsequent condensation of precursors for 30 minutes isothermal heat treatment at 70°C. The conversion after the preliminary treatment is still low and requires an additional heating to complete the reaction. Three different thermal treatments were investigated: conventional heating, infrared heating and microwave heating. DSC characterisation of the obtained samples evidenced a drastic reduction of the treatment time when microwaves were used, requiring only a few seconds, compared to the hours-lasting conventional treatments.

2005 - Perfluoropolyether-based Organic-Inorganic Hybrid Coatings: Preparation and Surface Characterization [Articolo su rivista]
Messori, Massimo; Toselli, M.; Pilati, Francesco; Fabbri, Paola; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; Tonelli, C.

not available

2005 - Perfluoropolyether-based organic-inorganic hybrid coatings: Preparation and surface characterisation [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; Fabbri, Paola; Pasquali, Luca; M., Montecchi; Nannarone, Stefano; C., Tonelli

Hydrophobic-oleophobic coatings were prepared by using the sol-gel process with organic-inorganic hybrids based on perfluoropolyether-polycaprolactone (PFPE-PCL) copolymers. Hybrid coatings were prepared by changing the organic-inorganic ratio, the PFPE/PCL ratio in the copolymer, and the reaction conditions. A complete surface characterisation was carried out by contact angle analysis and x-ray photoemission spectroscopy (XPS). In all cases the wettability of the coatings was found to be very low. Surface composition analysis showed that the surface segregation of the fluorinated PFPE segments was always high enough to give a very high hydrophobic character to the coating surface.

2005 - Perfluoropolyether-silica hybrids: preparation and surface characterization [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; Fabbri, Elena; Fabbri, Paola; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; C., Tonelli

α,ω-Triethoxysilane terminated perfluoropolyether-polycaprolactone block copolymers, TXCL(x)Si, were synthesised, characterised and subsequently reacted with tetraethoxysilane to prepare transparent organicinorganic hybrid materials by using the sol–gel process. Surface characterization was carried out through contact angle measurements. All the materials investigated (independently on both the reaction time of the sol–gel reaction before coating application and the bulk organic-inorganic ratio) showed a strong hydrophobic character when compared with non-fluorinated and fully inorganic control materials. The highest water contact angles were obtained when TXCL(x)Si oligomer used for the preparation of the hybrid contained short hydrogenated polycaprolactone segments. In all cases, the surface tension values indicated that the very surface at the air-coating interface showed almost completely perfluoropolyether segments.

2005 - Poly(caprolactone-co-lactide)/perfluoropolyether block copolymers: Synthesis, thermal, and surface characterization [Articolo su rivista]
R., Bongiovanni; G., Malucelli; Messori, Massimo; Pilati, Francesco; A., Priola; C., Tonelli; M., Toselli

Poly[(caprolactone-co-lactide)-b-perfluoropolyether-b-(caprolactone-co-lactide)] copolymers (TXCLLA) were prepared by ring-opening polymerization Of D,L-dilactide (LA2) and caprolactone (CL) in the presence of alpha,omega-hydroxy terminated perfluoropolyether (Fomblin Z-DOL TX) as macroinitiator and tin(H) 2-ethylexanoate as catalyst. H-1 NMR analysis showed that LA2 is initially incorporated into the copolymer preferentially with respect to CL. A blocky structure of the polyester segment was also indicated by the sequence distribution analysis of the monomeric units. Differential scanning calorimetry analysis showed the compatibility between poly(lactide) (PLA) and poly(caprolactone) (PCL) blocks inside the amorphous phase with glass-transition temperature values increasing from -60 to -15 degrees C by increasing the PLA content. Copolymers with high average length of CL blocks were semi-crystalline with a melting temperature ranging from +35 to +47 degrees C. Surface analysis showed a high surface activity of TXCLLA copolymers with values of surface tension independent from the PLA/PCL content and very close to those of pure TX.

2005 - Silane functionalization of perfluoroether oligomers for reaction management and morphology control of two-phase epoxy networks [Articolo su rivista]
L., Mascia; Vsy, Ng; Rh, Heath; Messori, Massimo

Mixtures of an epoxy resin, hardener, and acid functionalized perfluoroether oligomers will readily undergo phase separation during curing. However, the conditions to bring about the growth of nuclei into microscopic particles have hitherto been found only for systems cured with anhydrides. In the present study perfluoroether oligomers were functionalized by established procedures to introduce both carboxylic acid groups and alkoxysilane groups in sites within the chain extended segments. The presence of alkoxysilane groups together with the prereaction step with an excess epoxy resin, prior to the addition of the aromatic amine hardener, induced phase separation by a nucleation-and-growth mechanism. The dual functionality in the perfluoroether oligomer was even more beneficial when the alkoxysilane groups were hydrolyzed prior to the addition of the amine hardener. Under such circumstances the precipitation of the perfluoroether oligomer occurred quantitatively, as indicated by the complete absence of any plasticization effects in the epoxy matrix. From electron microscopy examinations, thermal analysis, and measurements of mechanical properties it was possible to deduce a plausible mechanism for the formation of the typical core-shell aggregates within the precipitated particles for these systems, which could also be applied to other systems, such as those using carboxylic-acid-terminated butadiene acrylonitrile oligomers.

2004 - Comparison Between Titanium Tetrabutoxide and a New Commercial Titanium Dioxide Based Catalyst Used for the Synthesis of Poly(Ethylene Terephthalate) [Articolo su rivista]
Finelli, L.; Lorenzetti, C.; Messori, Massimo; Sisti, L.; Vannini, M.

Titanium-based catalysts for poly(alkylene terephthalate) synthesis have been known for many years. Up to now, organotitanate compounds are used as catalysts on an industrial scale only for the synthesis of poly(butylenes terephthalate) (PBT), poly(trimethylene terephthalate) (PTT), and related copolyesters; for poly(ethylene terephthalate) (PET), synthesis antimony-based catalysts are preferred. In fact, in this case, titanium is known to cause undesirable discoloration. In this article, a study of PET synthesis using different concentrations of a new titanium dioxide based catalyst (C-94), commercially available from Acordis Industrial Fibers GmbH, is carried out and compared with the results obtained with titanium tetrabutoxide (TBT) catalyst in the same experimental conditions. The solid-state properties and composition of C-94 was investigated by thermogravimetric analysis (TGA) coupled with mass spectroscopy and by X-ray powder diffraction (XRD). A characterization of the polymers prepared with C-94 and TBT is also described. The results have shown that the use of C-94 leads to more hydrolytically stable polymers, whereas no evidence of difference in the catalytic activity, carboxyl end-groups concentration, diethylene glycol content, and thermal properties were revealed.

2004 - Prevention of plasticizer leaching from PVC medical devices by using organic-inorganic hybrid coatings [Articolo su rivista]
Messori, Massimo; A., Toselli; F., Pilati; Fabbri, Elena; P., Fabbri; Pasquali, Luca; S., Nannarone

α,ω-triethoxysilane terminated poly(ethylene oxide) (PEO-Si) was prepared and used to produce organic/inorganic hybrids by the sol–gel approach. These hybrids were used as coatings for flexible PVC tubes in order to reduce the plasticizer leaching from PVC medical devices. Extraction tests carried out with hexane indicated that all coating composition investigated are able to strongly reduce (about one order of magnitude) the leaching of di-ethylhexyl phthalate in hexane. The best results were obtained by an accurate balance of organic and inorganic phases content. XPS analysis showed a preferential segregation of silica onto the outer surface suggesting that a high inorganic content at the coating–extraction medium interface was present.

2004 - Surface modification of unsaturated polyester resins with perfluoropolyethers [Articolo su rivista]
Fabbri, Elena; Fabbri, Paola; Messori, Massimo; Pilati, Francesco; C., Tonelli; M., Toselli

Fluorine-modified unsaturated polyester resins (FUPR) were prepared by using polycaprolactone-perfluoropolyether-polycaprolactone triblock copolymers having hydroxyl or methacrylate end-groups. Despite the immiscibility of the perfluoropolyether segment, all the modified resins were fully transparent after curing thanks to the compatibilization effect of the polycaprolactone segments. Contact angle measurements showed a very low water wettability for all investigated resin compositions. Also in the case of system with the lower bulk copolymer concentration (less than 0.3 phr) contact angles were higher than 94°. It has been demonstrated that the presence of methacrylate end-groups tends to hinder the surface segregation of the fluorinated additive.

2003 - Flame Retarding Poly(Methyl Methacrylate) with Nanostructured Organic-Inorganic Hybrids Coatings [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; Fabbri, Elena; P., Fabbri; S., Busoli; Pasquali, Luca; S., Nannarone

Organic–inorganic hybrid materials were prepared starting from tetraethoxysilane and α- or α,ω-triethoxysilane terminated poly(ε-caprolactone) (PCL–Si) using the sol–gel process. In all cases the formation of nanocomposites with a high level of interpenetration between organic and inorganic phases was noted. Poly(methyl methacrylate) slabs were dip-coated with PCL–Si/silica hybrids and a very strong increase of the flame resistance (also after UV irradiation) was noted for all coating compositions without marked differences with respect to hybrid compositions. This behavior was attributed to a preferential segregation of silica onto the outer surface, as evidenced by XPS analysis.

2003 - New catalysts for poly(butylene terephthalate) synthesis. Part 3: Effect of phosphate co-catalysts [Articolo su rivista]
M., Colonna; Te, Banach; C., Berti; M., Fiorini; E., Marianucci; Messori, Massimo; Pilati, Francesco; M., Toselli

An exhaustive study of the co-catalytic activity of phosphates on titanium and titanium/hafnium based catalytic systems in poly(butylene terephthalate) synthesis was conducted in order to investigate any improvement in the process and/or in the properties of the final polymer with respect to the industrially used titanium based catalyst. Small scale polymerisation and subsequent scale up in higher capacity reactors showed a strong co-catalytic effect of phosphates. A screening on model compounds showed NaH2PO4 to be the most active co-catalyst. The co-catalysts had a stronger effect on titanium with respect to hafnium. Decreases in polymerisation time and tetrahydrofuran formation were observed, which in turn can improve the productivity of the whole process. Moreover, the use of phosphate improved the thermal stability of the final polymers. (C) 2003 Elsevier Science Ltd. All rights reserved.

2003 - Poly(caprolactone)/silica organic-inorganic hybrids as protective coatings for poly(methyl methacrylate) substrates [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; E., Fabbri; Fabbri, Paola; S., Busoli

Organic-inorganic hybrid materials (also known as ceramers or phase-interconnected nanocomposites) were prepared starting with tetraethoxysilane and α,ω-triethoxysilane-terminated poly(ε-caprolactone) (PCL-Si) using the sol-gel process. In all cases the formation of nanocomposites with a high level of interpenetration between PCL and SiO2 phases was noted. Poly(methyl methacrylate) (PMMA) slabs were dip-coated with PCL-Si/silica hybrids and a preferential segregation of silica on to the outer surface was found, together with a PCL-rich coating PMMA interface. In all cases, a marked reduction in both the average roughness and the apparent friction coefficient was noted with respect to the uncoated PMMA. All the PCL-Si/SiO2-coated samples showed a significant increase in flame resistance before and after UV irradiation, while improvements in the anti-scratch properties were noted only in the case of the PMMA coated with silica-rich ceramers.

2003 - Surface chemical analysis of poly(epsilon-caprolactone)-perfluoropolyether-poly(epsilon-caprolactone) triblock copolymers by X-ray photoelectron spectroscopy [Articolo su rivista]
M., Toselli; Ja, Gardella; Messori, Massimo; Am, Hawkridge; Pilati, Francesco; C., Tonelli

The air-side surface composition of a series of poly(e-caprolactone)-perfluoropolyether-poly(epsilon-caprolactone) triblock copolymers with different compositions and block lengths have been studied by angle-dependent X-ray photoelectron spectroscopy (XPS). The weight percentage of the perfluoropolyether (PFPE) and polycaprolactone (PCL) blocks, and ethylene oxide linker (RH) has been calculated in different ways: from C1s, O1s and F1s photoemission peaks and by line fitting of the C1s and O1s envelopes. The atomic sensitivity factors and the parameters used to fit the peak envelopes have been experimentally determined using some reference materials. A critical discussion of the different methods used in the surface characterization and the degradation of PFPE segments, induced by irradiation beam, have been also reported. A large excess of PFPE with respect to the bulk composition was observed in all samples, and the angular dependence of the XPS signal demonstrated that the content of the fluorinated block segment increased by decreasing the sampling depth. The PFPE surface concentration was also decreased by increasing the PCL/PFPE ratio, but the surfaces of the samples were still dominated by PFPE segments for copolymers with a bulk PFPE composition lower than 10%. Moreover, copolymers with similar PCL/PFPE bulk ratios but with different PFPE block lengths, showed similar PFPE surface composition when the number-average molecular weight (M.) was 2000 and 3200 g mol(-1), while that observed for copolymers containing PFPE block with M. 900 g mol(-1) was lower.

2002 - Poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) block copolymers as surface modifiers of poly(vinyl chloride) [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; Fabbri, Paola; C., Tonelli

Blends of poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) (PCL-PFPE-PCL) triblock copolymers (with different length of PFPE and PCL segments) and poly(vinyl chloride) (PVC) were prepared by casting from tetrahydrofuran solution. DSC analysis revealed a complex morphology deriving from miscibility between PCL and PVC segments. XPS analysis showed strong surface enrichment of PFPE segments for all films prepared. Treatment with a PFPE selective solvent showed that the fraction of PCL-PFPE-PCL removed from surface decreased with increasing length of PCL blocks, indicating an anchorage effect by PCL segments with respect to PVC matrix.

2002 - Synthesis and characterisation of silica hybrids based on poly (epsilon-caprolactone-b-perfluoropolyether-b-epsilon-caprolactone) [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; L., Mascia; C., Tonelli

Poly(epsilon-caprolactone-b-perfluoropolyether-b-epsilon-caprolactone) (PCL-PFPE-PCL) triblock copolymers having hydroxy end groups were readily functionalised with triethoxysilane end groups by reactions with 3-isocyanatopropyltriethoxysilane. Organic-inorganic hybrids were prepared by using the sol-gel process in the presence of tetraethoxysilane and hydroxy or triethoxysilane terminated PCL-PFPE-PCL. Fully transparent hybrid materials with high content of organic matter were obtained only in the case of alkoxysilane functionalised copolymers. For such systems the PCL-PFPE-PCL copolymer was so intimately mixed with the inorganic network to prevent crystallisation of the PCL segments, The progress of the sol-gel reaction was limited by the early vetrification of the reactive system, while the interpenetration of the organic phase was enhanced by curing the samples at 100 degreesC. (C) 2002 Elsevier Science Ltd. All rights reserved.

2001 - New catalysts for poly(butylene terephthalate) synthesis 1. Titanium-lanthanides and titanium-hafnium systems [Articolo su rivista]
Pilati, Francesco; T. E., Banach; C., Berti; M., Colonna; M., Fiorini; Messori, Massimo; E., Marianucci; M., Toselli

A complete study of the catalytic activity of lanthanide-, and hafnium acetylacetonate catalysts in PET synthesis was conducted in order to investigate any improvement in the process and/or in the properties of the final polymer with respect to the industrially used titanium tetrabutoxide (TBT) catalyst. Small scale polymerization and subsequent scale up in higher capacity reactors showed that TBT-Hf(acac)4 and TBT-La(acac)3 mixed catalysts were more active with respect to TBT as single catalyst. Decreases in polymerization time and THF formation were also observed, which in turn can improve the productivity of the whole process. Furthermore, for similar values of molecular weight, a lower melt viscosity (and thus better processability and crystallizability) was obtained by using mixed catalysts, presumably due to weaker interactions of the polymer terminal groups to lanthanum and hafnium metals with respect to titanium.

2001 - Poly(e- caprolactone)-poly(fluoroalkylene oxide)-poly(e-caprolactone) block copolymers as surface modifiers of poly(vinyl chloride) [Relazione in Atti di Convegno]
Messori, Massimo; M., Toselli; Pilati, Francesco; Fabbri, Paola

Blends of poly(caprolactone-b-perfluoropolyether-b-caprolactone) (PCL-PFPE-PCL) triblock copolymers (with different length of PFPE and PCL segments) and poly(vinyl chloride) (PVC) were prepared by casting from tetrahydrofuran solution. DSC analysis revealed a complex morphology deriving from miscibility between PCL and PVC segments. XPS analysis showed strong surface enrichment of PFPE segments for all films prepared. Treatment with PFPE selective solvent showed that the fraction of PCL-PFPE-PCL removed from surface decreased with increasing length of PCL blocks, indicating an anchorage effect by PCL segments with respect to PVC matrix.

2001 - Poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) block copolymers. 2. Thermal and surface properties [Articolo su rivista]
Pilati, Francesco; Messori, Massimo; M., Toselli; R., Bongiovanni; G., Malucelli; A., Priola; C., Tonelli

The thermal and the surface properties of PCL-PEPE-PCL block copolymers having different PCL and PFPE block lengths were investigated by DSC, contact angles and XPS measurements. DSC analysis reveals for all the copolymers the presence of different amorphous phases; the phase located at low temperature was attributed to the fluorinated moiety. Tm values also demonstrated that PCL crystallizes from a pure phase. XPS measurements showed a strong surface enrichment in PFPE with respect to the bulk. Contact angle values showed a hydrophobic character of the film surface even if the trend was found not depending on the fluorine concentration as detected by XPS: this behavior may be explained by the presence of very flexible blocks, providing a highly dynamic surface. These structures can be potentially used as additives for the formation of polymers having 'smart surfaces' with selective adhesive properties.

2001 - Unsaturated polyester resins modified with poly(epsilon-caprolactone)-perfluoropolyethers block copolymers [Articolo su rivista]
Messori, Massimo; M., Toselli; Pilati, Francesco; C., Tonelli

Poly(epsilon -caprolactone)-perfluoropolyether-poly(epsilon -caprolactone) block copolymers (TXCL) synthesised from Fomblin Z-DOL TX (TX) have been mixed with conventional unsaturated polyester resins (UPR) to prepare fluorine modified UPR (FUPR). A preliminary investigation on the compatibility of uncured FUPR systems has shown that the presence of PCL blocks leads to an enhancement of compatibility with respect to pure perfluoropolyether macromers. The compatibility tends to decrease by increasing the TXCL concentration in the mixture depending on both molecular weight and TX/PCL ratio. Also the morphology of FUPR after curing was strongly affected by the rate of curing and by a critical balancing of TX/PCL ratio and molecular weight of TXCL copolymers. Both transparent and opaque FUPR were obtained for the same composition at different curing rates; high curing rates (i.e. high concentration of initiator/activator) favoured the formation of transparent FUPR through a kinetic control of phase separation. Scanning electron microscopy (SEM) analysis was in good agreement with the macroscopic results obtained by visual inspection. XPS analysis showed a very strong surface enrichment in fluorinated segments, which increases by increasing the TX/PCL ratio. Mechanical tests showed a slight plasticization effect (compared to UPR control) together with a very strong improvement in the absorbed energy at break EB showing the best toughening effect for TXCL with intermediate TX/PCL ratio. Finally, a minimisation of the water diffusion coefficient value (five times lower than UPR control) was noted for UPR modified with TXCL having intermediate PCL segment length. (C) 2001 Elsevier Science Ltd. All rights reserved.

2000 - Acrylic polyester resins containing perfluoropolyethers structures: Synthesis, characterization, and photopolymerization [Articolo su rivista]
R., Bongiovanni; G., Malucelli; Messori, Massimo; Pilati, Francesco; A., Priola; C., Tonelli; M., Toselli

Poly(epsilon-caprolactone-b-perfluoropolyether-b-epsilon caprolactone) (PCL-PFPE-PCL) block copolymers having different PCL block lengths and end-capped with methacrylate groups were prepared and characterized. Spectroscopic analyses confirmed the expected molecular structure of the products. After UV curing, the films revealed the presence of two amorphous phases, corresponding to fluorinated and hydrogenated moieties, respectively. The material containing long PCL blocks showed also a crystalline phase. Surface properties of the UV-cured films were evaluated: The surfaces have a very high hydrophobic character in spite of the presence of many polar OH groups present in the polymeric network and a high hysteresis in wetting. An enrichment of fluorine at the air-side surface was shown by contact-angle measurements, except when long PCL sequences are present. The theta(adv) angles decreased by increasing the content of PCL, that is, by decreasing the content of fluorine.

2000 - Modifica del PVC per applicazioni biomedicali [Articolo su rivista]
Pilati, Francesco; Messori, Massimo; Fabbri, Paola; M., Toselli


1999 - Poly(epsilon-caprolactone)-poly(fluoroalkylene oxide)-poly(epsilon-caprolactone) block copolymers. 1. Synthesis and molecular characterization [Articolo su rivista]
Pilati, Francesco; M., Toselli; Messori, Massimo; A., Priola; R., Bongiovanni; G., Malucelli; C., Tonelli

Hydroxyl-terminated telechelic poly(fluoroalkylene oxide)s, (PFPE)s, with molecular weights ranging from 1100 to 3400 were employed as transfer agents for the ring-opening polymerization of epsilon-caprolactone (CL) in the presence of various catalysts/initiators. The highest conversion rate of CL was observed using Ti(OBu)(4) and Bu2SnO as catalysts/initiators. The polymerization of CL started only from the hydroxyl groups of PFPE, leading to the formation of ABA triblock copolymers without formation of homopolymer poly(epsilon-caprolactone) (PCL). The rate of insertion of the first unit of CL is much faster than the insertion of the other CL units, and the average molecular weight of the ABA copolymers was that expected by the CL/PFPE ratio. The polymerization rate of CL in the presence of PFPE using aluminum alkoxides as initiator was very slow, contrary to what is known about the homopolymerization of CL.

1999 - Polyester design considerations [Capitolo/Saggio]
Pilati, F.; Toselli, M.; Messori, Massimo


1999 - Principles of step polymerization [Capitolo/Saggio]
Pilati, Francesco; M., Toselli; Messori, Massimo


1998 - Unsaturated polyester resins modified with perfluoropolyethers [Articolo su rivista]
Pilati, Francesco; M., Toselli; Messori, Massimo; U., Credali; C., Tonelli; C., Berti

Telechelic macromers based on hydroxyterminated perfluoropolyethers (HO-R-H-PFPE-R-H-OH) with different molecular weights were used for the preparation of fluorine-containing unsaturated polyester resins (FUPR). The products resulting from the reaction of the monomers usually employed for the preparation of unsaturated polyesters with HO-R-H-PFPE-R-H-OH were in any case milky liquids. The degree of reaction of the hydroxyl terminal groups of HO-R-H-PFPE-R-H-OH was monitored by H-1-NMR analysis on the fractions collected after sedimentation experiments; amount and composition of the sediment and sedimentation rate were found dependent on both the molecular weight of fluorinated macromer and the method used for polyesterification. The molecular weight of HO-R-H-PFPE-R-H-OH and the reaction conditions had also a strong influence on the final morphology of crosslinked polymers. A very poor interphase adhesion was observed when unreacted HO-R-H-PFPE-R-H-OH was blended with the unsaturated polyester. On the contrary, when the fluorinated macromer was allowed to react during polyesterification, the adhesion of the fluorine-rich dispersed phase to the unsaturated polyester matrix was good for low molecular weight HO-R-H-PFPE-R-H-OH and when the fluorinated prepolymer had been modified by a previous reaction with chlorendic anhydride, but it was poor, as for unreacted macromers, for high molecular weight HO-R-H-PFPE-R-H-OHs. FUPRs prepared using a low molecular weight HO-R-H-PFPE-R-H-OH exhibited a significant improvement of the flexural strength even at very low level of addition (3% by wt).

1997 - On specific factors affecting the crystallization of PET: role of carboxyl terminal groups and residual catalysts on the crystallization rate [Articolo su rivista]
Pilati, Francesco; M., Toselli; Messori, Massimo; C., Manzoni; A., Turturro; E. G., Gattiglia

The non-isothermal crystallization rate of poly(ethylene terephthalate) (PET) has been studied in differential scanning calorimetry experiments, by cooling from the molten state of samples of various molecular weights, prepared using various catalysts (mainly Ti(OBu)4). The crystallization temperature, Tc, was obviously influenced by the molecular weight, but also by the carboxyl group content, by the type of residual catalyst, by dissolution-reprecipitation treatments and by re-melting phenomena. The observed effects were interpreted assuming that interactions of terminal groups of the PET chains (mutual or with residual catalyst) led to an apparent increase in molecular weight, which in turn determined a decrease in the chain mobility and was responsible for a decrease in the rate of crystallization. Thus, a higher concentration of carboxyl terminal groups as well as interactions of PET terminal groups with the catalyst decreased Tc. Any factor which was able to destroy these interactions (treatments of dissolution-reprecipitation, phosphorous derivatives, aging) led to an increase of the overall crystallization rate.

G. L., Castiglioni; A., Guercio; Messori, Massimo; A., Vaccari

The reactivities of the main products observed in the vapour phase hydrogenation of maleic anhydride (MA) were investigated separately, using a multicomponent catalyst (Cu/Zn/Mg/Cr=40:5:5:50, atomic ratio %), obtained by reduction of a non-stoichiometric spinel-type precursor. Tetrahydrofuran (THF) reacted only at high temperature forming small amounts of ethanol (EtOH), while gamma-butyrolactone (GBL) gave rise, with high conversion, to overhydrogenation [to butyric acid (BuA) or n-butanol (BuOH)] and/or hydrogenolysis [mainly to EtOH. Furthermore, the formation in the catalytic tests with BuA and BuOH of n-butanal (notwithstanding the high H-2/organic ratio), suggested it as the main intermediate in the hydrogenolysis reaction. Therefore, a new reaction scheme is proposed, evidencing the key role of GBL as the ''intersection'' of two possible reaction pathways, giving rise to THF or unwanted and low-cost by-products. Because of the increasing restrictions on the use of Cr-containing catalysts, the research was extended to include an investigation of the reactivity of Al-containing catalysts, also prepared by reduction of spinel-type precursors. These catalysts, in particular those with low copper contents, gave rise to high productions of GEL, favouring also the formation of THF and reducing the amounts of unwanted and low-cost by-products. It was shown that a Cu/Zn/Al=25:25:50 (atomic ratio %) composition may represent a useful compromise, allowing good yields in GBL to be obtained at lower reaction temperatures.

Messori, Massimo; A., Vaccari

The catalytic reactivity of maleic anhydride (MA), succinic anhydride (SA) and their dimethyl esters (dimethyl maleate and dimethyl succinate) in the vapour phase hydrogenation to gamma-butyrolacetone (GBL) was investigated. In order to obtain general data, both a multicomponent catalyst (CAT 1: Cu/Zn/Mg/Cr 40:5:5:50, atomic ratio %), obtained by reduction of a nonstoichiometric spinel-type precursor, and a commercial catalyst (CAT 2: Cu/Mn/Ba/Cr = 44:8:1:47, atomic ratio %) were used. The MA/GBL solution exhibited the highest GBL production, while the SA/GBL solution was converted only partially due to a competitive adsorption of GBL on the active sites, as evidenced by the similar reactivities observed with pure anhydrides. The best carbon balances were observed with the esters, probably the result of lowest light hydrocarbon synthesis and tar formation. With all the feedstocks, the activity of CAT 2 is higher than that of CAT 1, which, however, gives the best yield in GBL due its lower activity in the overhydrogenation and hydrogenolysis reaction. It was found that n-butanol (BuOH) and butyric acid (BuA) derived mainly from GBL. On this basis, the reactivities of the main products observed were investigated separately, confirming the stability of tetrahydrofuran (THF), which reacted only at high temperature with low conversions to ethanol. On the other hand, GBL gave rise to overhydrogenation and/or hydrogenolysis, with high conversion (mainly with CAT 2), confirming its key role in both reactions. Furthermore, the formation in the catalytic tests with BuA and BuOH of n-butanal, notwithstanding the high H-2/organic ratio, implies that it is the main intermediate in the hydrogenolysis reactions. A new reaction scheme is proposed, pointing out the key role of GBL as the ''intersection'' of two possible reaction pathways, giving rise to THF or overhydrogenation and hydrogenolysis products, respectively.

G., Golinelli; F., Trifiro; M., Baerns; F., Majunke; Messori, Massimo; B., Grzybowska; J., Czekaj; B., Majka; C., Dias; M., Portela

The selective oxidation of o-xylene to phthalic anhydride has been studied in four laboratories, using catalysts EL10V1 and EL10V8; conversions and product yields as a function of time-on-stream are reported. The results obtained are in generally good agreement: for both catalysts, phthalic anhydride yields at 40% conversion are ca. 20%, rising to 63-70% at 100% conversion. Increasing the vanadium content from 1 to 8% has little effect and may even result in a slightly worse performance. Differences in the temperatures required to attain a fixed conversion may reflect differences in reactor design, especially with regard to heat exchange efficiency.

G. L., Castiglioni; C., Fumagalli; A., Guercio; R., Lancia; Messori, Massimo; G., Stefani; A., Vaccari

Cubic spinel-type phases containing excess copper ions may be obtained by controlled oxidation of homogeneous copper-rich coprecipitates. Partial substitution of the copper ions with other divalent cations leads to considerable modifications in both thermal stability and catalytic properties. Cadmium ions give rise to dramatic deactivation in the hydrogenation of maleic anhydride (MA), while zinc ions favour the hydrogenation of succinic anhydride (SA) to gamma-butyrolactone (GBL). On the other hand, the partial substitution with Mg2+ ions increases the productivity in GBL, inhibiting the reactions of over-hydrogenation and/or hydrogenolysis. When both Mg2+ and Zn2+ ions are present production of GBL is higher and hydrogenolysis essentially does not occur. Furthermore, the Cu/Zn/Mg/Cr catalyst investigated in reaction conditions of industrial interest did not show any scale-up problems or deactivation phenomena with increasing time-on-stream.

G. L., Castiglioni; C., Fumagalli; A., Guercio; R., Lancia; Messori, Massimo; A., Vaccari

Not only catalyst composition, but also temperature, pressure and H2/C4 ratio play important roles in vapour phase hydrogenation of maleic anhydride (MA) to gamma-butyrolactone (GBL), affecting both MA conversion and GBL yield. Pressure determines the GBL <-> BDO equilibrium (notwithstanding the presence of excess hydrogen), the H2/C4 ratio affects catalyst activity and life, and the optimum reaction temperature depends considerably on catalyst composition. On the contrary, high temperature activation and regeneration by thermal desorption under high hydrogen flow do not show any advantages. Furthermore, by comparing the catalytic reactivity of MA, succinic anhydride (SA) and their dimethyl-esters (DMM and DMS), it was shown that MA may be considered an actual alternative to ester hydrogenation in GBL production. Low conversion was observed with SA/GBL solution and attributed to a competitive adsorption of GBL on the active sites of the catalyst.

C., Fumagalli; G., Golinelli; G., Mazzoni; Messori, Massimo; G., Stefani; F., Trifiro

Vanadium is a key element in the formulation of catalysts for the production of anhydrides by selective vapor oxidation with molecular oxygen. A study of the oxidations of o-xylene, n-butane and benzene on V-P, V-Mo and V-Ti mixed oxides, the commercial catalysts for the synthesis of anhydrides, was carried out. The oxidation of o-xylene on the three catalysts was the most facile reaction leading to high yields in phthalic anhydride; on the contrary in the oxidation of n-butane only V-P mixed oxide was active and selective. V-P mixed oxide is active and selective in the oxidation of all the feedstocks and can be identified as the most polyfunctional catalyst. V-Mo is active and selective in both o-xylene and benzene oxidation and V-Ti only in o-xylene oxidation. Moreover the lesser selectivity in phthalic anhydride observed with V-P and V-Mo mixed oxides has been attributed to parallel oxidation reactions to the formation of phthalic anhydride, evidenced by a higher amount of phthalide.

G. L., Castiglioni; C., Fumagalli; R., Lancia; Messori, Massimo; A., Vaccari