Crystalline morphology, thermal properties, and enzymatic degradability of (R)-3-hydroxybutyric acid-based copolyesters

The solid-state structures, thermal properties, and enzymatic degradability of melt-crystallized films of random copolymers of (R)-3-hydroxybutyric acid (3HB) with different hydroxyalkanoic acids were investigated. The crystallinity, lamellar thickness, and spherulite growth rate of copolymers decreased with an increase in the carbon numbers of second monomer units for copolymers with an identical comonomer composition. The enzymatic degradation rate of random copolyesters decreased with increases both in the crystallinity and in the lamellar thickness. As the results, the rate of enzymatic erosion could be accelerated by the incorporation of second monomer units with more large steric bulkiness.