Controlling the biodegradation rates of poly(globalide-co-ε-caprolactone) copolymers by post polymerization modification

Abstract: Controlling the degradation rates of polymers is crucial for their application in tissue engineering or to achieve degradation of the polymers in the wastewater purification. As hydrophobic polyesters often exhibit very slow degradation rates, we report here increased biodegradation rates of poly(globalide-co-{\epsilon}-caprolactone) copolymers (PGlCL) produced by enzymatic ring-opening copolymerization and post-functionalized with N-acetylcysteine by thiol-ene reaction. The degradation rates of the PGlCL and post-modified PGlCL-NAC films were determined by weight-loss experiments. The polymer films were immersed in phosphate-buffered saline (PBS) solution, and PBS containing lipase from Pseudomonas cepacia. The degree of functionalization affected the degradation behavior, and samples with a higher degree of functionalization presented higher weight loss. Finally, a degradation assay was performed in activated sludge, and PGlCL-NAC presented high degradability, having a degradation behavior similar to starch. Density Functional Theory (DFT) calculations were used to assess the changes in chemical properties and electronic charge distribution of PGlCL after its functionalization with NAC, helping to understand its influence in their degradability. The results obtained confirm the possibility to increase the degradation rates of copolyesters based on caprolactone and globalide by thiol-ene post-functionalization, being a promising alternative for applications in biomedicine or the packaging sector.