Polycarbonates derived from propylene oxide, CO2, and 4-vinyl cyclohexene oxides terpolymerization catalyzed by bifunctional salcyCoIIINO3 complex and its post-polymerization modification

Terpolymerizations of CO2, propylene oxide (PO), and 4-vinyl cyclohexene oxide (VCHO) were successfully catalyzed by a single cobalt(III) complex of a salen-type ligand bearing one quaternary ammonium salt on the five-position of each aromatic ring. The influences of various reaction conditions such as molar ratio of the monomers, reaction time and reaction temperature on the terpolymerization progress were investigated. The resulting terpolymers showed only one thermolysis peak and one adjustable glass-transition temperature (Tg) dependable on vinyl cyclohexene carbonate (VCHC) unit content with the relationship of "Tg (°C) = 64 × FVinyl + 39". Furthermore, the epoxy group was incorporated by oxidation of vinyl group of PVCHC units and the cyclic carbonate (CC) functional group was achieved by reaction of CO2 with epoxy-functionalized terpolymer. The linear dependencies of the Tg on the mole fractions ratio of pendent epoxy and CC groups on the poly(cyclohexene carbonate) main chain were also observed. Notably, the Tg of fully CC-functionalized PCHC was up to 196 °C, which was the highest Tg of CO2-based polycarbonate reported at the absence of cross-linked structure.