(CO)POLYMERS OF L-LACTIDE .1. SYNTHESIS, THERMAL-PROPERTIES AND HYDROLYTIC DEGRADATION

Copolymers of L-lactide(a)) with D-Lactide(a)), glycolide(b)), epsilon-caprolactone and trimethylene carbonate, and networks with spiro-bis-dimethylene-carbonate (2,4,7,9-tetraoxaspiro[5.5]undecane-3,8-dione) were prepared in bulk at standardized polymerization conditions. The properties of the nascent copolymers were evaluated with respect to the nature of the comonomer. Copolymerization with comonomers entailing low glass transition temperature simultaneously reduces the crystallinity. 300 MHz H-1 nuclear magnetic resonance is shown to be a useful technique for the determination of the average monomer sequence lengths in epsilon-caprolactone and trimethylene carbonate copolymers. The presence of crystallizable L-lactide sequences, due to differences in monomer reactivity, has a large effect on the thermal properties of the copolymer as well as on the long-term degradation characteristics.