Noncopolymerization Approach to Copolymers via Concurrent Transesterification and Ring-Opening Reactions

Inter- and intrachain transesterification, normally regarded as a detrimental side reaction for the synthesis of polyesters, is utilized herein to formulate a novel strategy for the modification of polyesters. Addition of an organic superbase into the mixture of hydroxyl-terminated poly(epsilon-caprolactone) and an epoxide, for example, propylene oxide or 1,2-butylene oxide, triggers concurrent nucleophilic ring-opening of the epoxide and transesterification reaction. The synergetic effect enables convenient and efficient transformation of the polyester into poly(ester ether) random copolymers and thus advances the preparation of functional degradable polymeric materials taking advantage of the variety of commercial and laboratory-made polyesters and epoxides.