Dual catalysis for the copolymerisation of epoxides and lactones.

A dual catalysis system was developed to synthesize hydrolyzable polyether-polyester copolymers from propylene oxide and cyclic esters such as gamma-butyrolactone, delta-valerolactone, and epsilon-caprolactone. A bimetallic chromium catalyst active for the enantioselective polymerisation of propylene oxide and an organocatalyst active for the ring-opening polymerisation of lactones were used in conjunction with an alcohol chain shuttling agent to create new copolymers. The monomer and alcohol ratios were varied to yield a wide range of copolymers with varying monomer ratios, molecular weights, and crystallinities.