Highly branched linear-comb random copolyesters of ε-caprolactone and δ-valerolactone: Isodimorphism, mechanical properties and enzymatic degradation behavior

摘要

In this work, a series of highly branched linear-comb random copolyesters of epsilon-caprolactone (CL) and delta-valerolactone (VL) with high molecular weight and narrow distribution in various compositions were successfully synthesized. The composition-dependent microstructure, thermal and mechanical properties, and enzymatic degradation behavior of the resulting copolyesters were investigated systematically. The cocrystallization behavior was observed for the highly branched linear-comb random CL/VL copolyesters over the entire composition range, and a pseudo-eutectic point of isodimorphism occurred at about 50 mol% VL incorporated in copolymer. The obtained copolymers displayed lower Young's modulus, yield strength, and breaking strength, but higher elongation at break. Furthermore, the copolymers presented much higher degradation rate during enzymatic degradation process in comparison with parent homopolymers. More importantly, it was found that both mechanical properties and degradation behavior showed a similar pseudo-eutectic behavior of isodimorphism. Consequently, the correlation among of isodimorphism, mechanical properties, and degradation behavior depending on composition is highly significant, and the physical properties and degradation rate of the isodimorphic copolyesters could be continuously tailored by the feedstocks. (C) 2018 Elsevier Ltd. All rights reserved.