Postpolymerization Functionalization of Copolymers Produced from Carbon Dioxide and 2-Vinyloxirane: Amphiphilic/Water-Soluble CO₂-Based Polycarbonates

Common CO2-based polycarbonates are known to be highly hydrophobic, and this “inert” property makes them difficult for the covalent immobilization of bioactive molecules. A practical method for modifying polymers is to introduce various functional groups that permit decoration of polymer chains with bioactive substances. In this report, CO2-based poly(2-vinyloxirane carbonate) (PVIC) with more than 99% carbonate linkages is isolated from the CO2/2-vinyloxirane alternating copolymerization catalyzed by the bifunctional catalyst [(1R,2R)-SalenCo(III)(DNP)2] (1) (DNP = 2,4-dinitrophenolate) bearing a quaternary ammonium salt on the ligand framework. It was also observed that the presence of propylene oxide significantly activates 2-vinyloxirane for incorporation into the polymer chain as well as inhibits the formation of cyclic carbonate in the terpolymerization process. DSC studies demonstrate that the glass transition temperature (Tg) decreases with the increase in the content of vinyl groups in the polyca...