(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) w ere prepared in bulk at standardized polymerization conditions. The pr operties of the nascent copolymers were evaluated with respect to the nature of the comonomer. Copolymerization with comonomers entailing lo w glass transition temperature simultaneously reduces the crystallinit y. 300 MHz H-1 nuclear magnetic resonance is shown to be a useful tech nique for the determination of the average monomer sequence lengths in epsilon-caprolactone and trimethylene carbonate copolymers. The prese nce of crystallizable L-lactide sequences, due to differences in monom er reactivity, has a large effect on the thermal properties of the cop olymer as well as on the long-term degradation characteristics.