Zinc glutarate catalyzed synthesis and biodegradability of poly(carbonate-co-ester)s from CO2, propylene oxide, and ε-caprolactone

A zinc glutarate (ZnGA) catalyst was prepared from the reaction of zinc oxide and glutaric acid in dry toluene. ZnGA was found to exhibit a catalytic activity for the copolymerization of carbon dioxide (CO2) and propylene oxide (PO) and the homopolymerization of PO but to reveal no catalytic activity for the hornopolymerization of epsilon-caprolactone (CL). The ZnGA-catalyzed polymerization was extended for the terpolymerization of CO2 with PO and CL, producing poly(propylene carbonate-co-epsilon-caprolactone)s (PPCCLs) with a reasonably high molecular weight in high yields. In the terpolymerization, PO and CL were used as both co-monomers and reaction media, after the reaction completed, the excess co-monomers were easily recovered and reused in the next terpolymerization batch. For the synthesized polymers, enzymatic and biological degradability were investigated.