Synthesis and biodegradability of copolymers of ethylene carbonate with lactones

The copolymers of ethylene carbonate (EC) with epsilon-caprolactone (CL) or delta-valerolactone (VL) were synthesized using (C5Me5)(2)SmMe(THF) as ini tiator. We prepared EC/CL and EC/VL copolymers with a high molecular weight (M-n greater than or equal to 140000) without decarboxylation from the EC unit. The EC/CL copolymers were obtained in a higher carbonate content (up to ca. 30 mol%) and in a better yield compared with EC/VL copolymers. The H -1 NMR and thermal analyses revealed that these copolymers exhibit random a rrangement. The enzymatic degradations of EC/lactone copolymers were invest igated using lipoprotein lipase and cholesterol esterase (both from Pseudom onas sp.). The degradability of the copolymers was much improved compared w ith that of lactone homopolymers. Greater degradation was observed for the lipase-induced degradation than the cholesterol esterase. The biodegradabil ity of these copolymers in natural environments (viz., in activated sludge and seawater) was examined. As compared with enzymatic degradations, simila r good biodegradability was observed for EC/CL copolymers, while a poor deg radation was seen for EC/VL copolymers.