Lipase-catalyzed ring-opening polymerization of lactones in the presence of aliphatic polyesters to ester copolymers

Ring-opening polymerization of macrolides in the presence of aliphatic polyester has been performed using Pseudomonas lipase as catalyst to produce ester copolymers with molecular weights of several thousands. The polymerization behavior was monitored by SEC and NMR. 13C NMR analysis showed that the resulting polymer was not a mixture of the starting polyester and the polymer from macrolide, but a random copolymer consisting of both units. These data indicate that the lipase catalysed the polymerization of the macrolide as well as the intermolecular transesterification of the starting and resulting polymers. The random copolymer was found to be highly crystalline by DSC and WAXD measurement. The present specific catalysis of the lipase was applied to the synthesis of ester copolymers by transesterification between two different polyesters.