One‐Pot Synthesis of Polycarbonate‐b‐Polyester Block Copolymers From CO₂/Epoxide/ε‐Caprolactone Catalyzed by Salen‐Cobalt(III) Complex

ABSTRACT

A Salen‐Co(III)‐Cl catalyzed copolymerization strategy is developed for the controlled synthesis of polycarbonate‐b‐polyester block copolymers through a one‐pot process involving CO₂, 4‐vinyl‐1‐cyclohexene‐1,2‐epoxy (VCHO), and ε‐caprolactone (ε‐CL). This procedure is extended to the copolymerization of CO₂, VCHO, and lactide. The catalytic system is designed and optimized with temperature and CO₂ acting as triggers to switch between CO₂/epoxide copolymerization and ε‐CL homopolymerization. In addition, introducing water as the chain transfer agent reduced the polydispersity index (PDI) of the block copolymers. The copolymer composition can be controlled by adjusting the concentration ratio of epoxides and ε‐CL, yielding copolymers with carbonate molar ratios ranging from 14% to 67%. The block copolymers exhibit enhanced thermal stability, and the glass transition temperature (T _g) can be controlled by adjusting the block composition.