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GIULIA SCURANI

Dottorando
Dipartimento di Scienze Chimiche e Geologiche

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Pubblicazioni

2023 - A PETase enzyme synthesised in the chloroplast of the microalga Chlamydomonas reinhardtii is active against post-consumer plastics [Articolo su rivista]
Di Rocco, G.; Taunt, H. N.; Berto, M.; Jackson, H. O.; Piccinini, D.; Carletti, A.; Scurani, G.; Braidi, N.; Purton, S.
abstract

Polyethylene terephthalate hydrolases (PETases) are a newly discovered and industrially important class of enzymes that catalyze the enzymatic degradation of polyethylene terephatalate (PET), one of the most abundant plastics in the world. The greater enzymatic efficiencies of PETases compared to close relatives from the cutinase and lipase families have resulted in increasing research interest. Despite this, further characterization of PETases is essential, particularly regarding their possible activity against other kinds of plastic. In this study, we exploited for the first time the use of the microalgal chloroplast for more sustainable synthesis of a PETase enzyme. A photosynthetic-restoration strategy was used to generate a marker-free transformant line of the green microalga Chlamydomonas reinhardtii in which the PETase from Ideonella sakaiensis was constitutively expressed in the chloroplast. Subsequently, the activity of the PETase against both PET and post-consumer plastics was investigated via atomic force microscopy, revealing evidence of degradation of the plastics.

2023 - A Trifunctional ATRP Initiator Bearing Adaptable Bonds [Poster]
Scurani, Giulia; Braidi, Niccolo'; Porcelli, Nicola; Tassinari, Francesco; Parenti, Francesca
abstract

Atom Transfer Radical Polymerization (ATRP) allows for the production of polymers with precise control over molecular weight, dispersity, topology, composition, and functionality. Functional groups can be introduced into the polymer through post-functionalization of chain ends, or on the alkyl residue of the initiator, or by introducing functionalized (co)monomers, greatly greatly enhancing the targetable applications. In addition, the desired functional group can also be carried by the ATRP initiator. Some researchers have explored initiators with hydrolysis- or heat-sensitive functionalities to impart self-healing properties to the final polymer. However, the commonly used aliphatic halide ester initiators have shown poor thermal stability. To address this issue, we recently developed a novel bifunctional benzamide-containing initiator employed in ARGET ATRP of styrene, demonstrating enhanced thermal stability. Covalent Adaptable Networks (CANs) have emerged as a solution for improving the recyclability of thermoset materials. CANs can reorganize connectivity between chains upon thermal treatment, enabling reprocessing. Our goal is to modify the structure of the benzamide-containing initiator to develop a trifunctional initiator bearing adaptable bonds.

2023 - Influences of nitrogen base excess on ARGET ATRP of styrene with ascorbic acid acetonide and traces of oxygen and water [Articolo su rivista]
Braidi, N; Parenti, F; Scurani, G; Tassinari, F; Buffagni, M; Bonifaci, L; Cavalca, G; Pettenuzzo, N; Ghelfi, F
abstract

Ascorbic acid is a promising regenerating agent for Activators ReGenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET ATRP) thanks to its sustainability and environmental friendlyness. The ascorbate anion has even more potential because it has a higher kinetic rate constant of reduction toward the copper catalyst than its protonated counterpart. Although ascorbic acid can be easily neutralized with inorganic bases, the resulting heterogeneous system in the polymerization of hydrophobic monomers (such as styrene) is not well-suited for industrial applications. To overcome this problem, in this study we investigate the use of ascorbic acid acetonide, a more lipophilic derivative, together with soluble nitrogen bases of different basicity. The results show how the pK(a) of the protonated form of the nitrogen base affects the process, especially in the presence of traces of water and/or oxygen. Additionally, we report that milder bases yield better results in terms of dispersity and chain-end fidelity, while high pK(a) bases lead to a complete loss of control.

2022 - Basicity Can Choregraph Regeneration in Homogeneous ARGET ATRP of Styrene [Poster]
Braidi, Niccolo'; Galanti, Marco; Scurani, Giulia; Parenti, Francesca
abstract

There are two drawbacks in the use of H2AA when polymerizing a hydrophobic monomer such as styrene. First, the low solubility of the reducing agent in non-aqueous solvents. Second, the reduction kinetic rate constant of the catalyst by H2AA is around two-orders of magnitude lower than that of ascorbate (HAA–). In non-dissociating solvents this means that the polymerization is much slower since it is strictly related to the amount of reduced catalyst. To overcome this, we employed for the first time a more lipophilic ascorbic acid derivative (5,6-isopropylidene ascorbic acid) in place of H2AA, complemented by nitrogen bases of varying basicity: trimethylpyridine (TMP), diisopropylethylamine (DIPEA), and 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). The resulting system is an efficient and effective, homogeneous ARGET ATRP of styrene. Furthermore, it highlighted how basicity influences the concentration of radicals, and thus control over the final product.

2022 - Novel Bifunctional Amide-Based Initiator for the Atom Transfer Radical Polymerization of Styrene with Ascorbic Acid Acetonide as Reducing Agent [Poster]
Scurani, Giulia; Braidi, Niccolo'; Tassinari, Francesco; Parenti, Francesca
abstract

This study focuses on the synthesis and characterization of a new bifunctional benzamide initiator, CMB2HexDA, for the production of thermostable α,ω-dichloropolystyrene via ARGET ATRP. The motivation behind this research is the need to obtain functionalized polystyrene that can withstand the high temperatures used in industrial extrusion processes, as well as the previous development of a method to obtain α,ω-dialkenepolystyrene by solventless thermal dehydrohalogenation. The commonly used initiators in ATRP undergo thermal fragmentation, leading to chain length reduction and loss of telechelicity. The synthesized initiator was purified and characterized, and the resulting α,ω-dichloropolystyrenes were analyzed through GPC and NMR. The telechelic polystyrene produced with the new initiator exhibited enhanced thermal stability compared to aliphatic-halide ester initiators. Although the specific diamine used does not confer specific functionality, the developed synthetic pathway allows for the introduction of other functionalities into thermostable polystyrenes. Furthermore, the benzamidic function could be exploited to achieve controlled chemical degradation of polystyrene, resulting in more readly degradable oligomeric fragments.