SYNTHESIS AND HYDROLYTIC DEGRADATION BEHAVIOR OF HIGH-MOLECULAR-WEIGHT L-LACTIDE AND GLYCOLIDE COPOLYMERS

High-molecular-weight copolymers of l-lactide and glycolide have been synthesized. The influence of the glycolide content on the mechanical and thermal properties of the as-polymerized copolymer was studied. Excellent mechanical properties and a large melting-point depression were observed. The dyad splitting of the carbonyl carbon atoms in the 13C nuclear magnetic resonance spectrum was used to determine the average length of the monomer sequences. It was found that the synthesized copolymers did not reveal a truly random monomer distribution. Hydrolytic degradation of a copolymer containing 27 mol% glycolide showed that large amounts of highly crystalline material were still present after 140 days, and that 10 mol% glycolide has been incorporated in the poly(l-lactide) lattice. © 1990.