One-pot copolymerization of epoxides/carbon dioxide and lactide using a ternary catalyst system

Poly(propylene carbonate) (PPC) and polylactide (PLA), two major types of biodegradable polymers, are produced by the cooperative ring-opening polymerization (coROP) of propylene oxide and CO2 and by the ring-opening polymerization (ROP) of lactide. Because of the incompatibility between coROP and ROP, only simple copolymers of PPC and PLA with up to three blocks have been synthesized. A hybrid of these two polymers would produce a new family of polymers. The new polymers would be regarded as promising biodegradable materials because they would combine the desirable properties of PPC and PLA. Here, we report the synthesis of a PLA/PPC multiblock copolymer using a novel ternary catalytic system that proceeds via an intermolecular chain transfer mechanism. The resultant polymer, which is 100% biodegradable, shows enhanced thermal properties stemming from the incorporation of the PPC units. The broad applicability was further confirmed by extension to other monomers and catalysts.