Ref.: MpoBi06-004
Apresentador: Amanda Vasconcelos Farias
Autores (Instituição): Farias, A.V.(Universidade Federal de Santa Catarina); Giovanardi, G.(Universidade Federal de Santa Catarina); Agner, T.(Universidade Federal de Santa Catarina); Araújo, P.H.(Universidade Federal de Santa Catarina); Sayer, C.(Universidade Federal de Santa Catarina);
Resumo:
Polyesters derived from macrolactones are recognized for their intrinsic biodegradability and biocompatibility, attributes that make them highly suitable for a variety of applications. Among these polymers, poly(globalide) (PGl), derived from the monomer globalide, stands out and has been the subject of recent investigations with potential applications in biomaterials. To broaden the spectrum of applications, it is possible to introduce terminal groups at the ends and side chains of these polymers, allowing the production of functional polyesters adaptable to specific demands. Enzymatic ring-opening polymerization (eROP) emerges as an essential technique for the synthesis of these polymers, enabling the use of cyclic monomers under mild and controlled conditions. The initiator allows molecular weight control by varying the ratio of initiator (I) to monomer (M). Functional initiators for e-ROP offer a direct route to the synthesis of aliphatic polyesters, subject to post-polymerization derivation. Despite its effectiveness, solvents such as DCM and THF can be harmful to health. 2-Methyltetrahydrofuran (2-MeTHF), a biobased solvent with similar solubility properties, presents itself as an attractive alternative. In this study, e-ROP of Gl initiated by N-Hydroxyethylacrylamide (HEAA) was performed in solution using Novozyme 435 as a biocatalyst. Before each reaction, the enzyme (40°C) and Gl (80°C) were dried in a vacuum oven for 24 hours in the presence of molecular sieves. The molar ratio I/M was 1:5 and the e-ROP was performed under N2 atmosphere and under magnetic stirring for 1 h at 65 °C. The polymer was precipitated with an excess of cold methanol for 24 h, vacuum filtered, and dried at 30 °C for 24 h. The assignment of the chemical structure and molecular weight was determined using 1H-NMR at 400 MHz and GPC. The characteristic peaks of the repeating units (2H, ? = 3.63–3.68 ppm) and the terminal groups of HEAA (2H, ? = 5.66–5.69 ppm) were identified. The reaction yield was approximately 86.7%. GPC analysis indicated a unimodality in the main peak of the polymer, suggesting the formation of a single species. The molecular weight predicted by 1H-NMR and GPC are in good agreement (MnRMN = 2261 g/mol and MnGPC = 3841 g/mol). Discrepancies between the molecular weight obtained from GPC and 1H-NMR spectroscopy may arise from GPC being calibrated to polystyrene standards, which have a different hydrodynamic volume compared to PGl. Additionally, 1H-NMR does not have a lower calibration limit, resulting in the consideration of oligomers in the estimated molecular weight. The dispersity remained reasonably low (? = 1.62). The results show that, even with moisture control, the water content in the enzymes influences the initiation of the chains. The need to explore alternative initiators, such as HEAA, is important as they offer more precise control over the functionality of the final polymer.