Copolymerization of propylene oxide and CO2 catalyzed by dinuclear salcy–CoCl complex

The development of catalytic systems is always a research focus on the field of epoxides/carbon dioxide (CO2) copolymerization. A novel bimetallic Cobalt complex (1) bearing a piperazine-bridged salcy ligand and ancillary chloride group (salcyCoCl) has been exploited as catalyst for the ring-opening copolymerization (ROCOP) of propylene oxide (PO) and CO2 to afford poly(propylene carbonate) (PPC). The catalyst loading, CO2 pressure, polymerization temperature, reaction time, type of cocatalyst were employed in order to explore the influences on the polymeration activity of 1. It was found that after adding the cocatalyst PPNCl, the bimetallic salcy?CoCl complex can exhibit relatively good activity under mild conditions in the catalytic copolymerization of PO and CO2. A reasonable bimetallic polymerization mechanism has been proposed according to the polymer structure and the interaction between metal complex catalyst system and monomer.