Ring‐opening copolymerization of epoxycyclohexane and phthalic anhydride catalyzed by the asymmetric Salen‐CrCl complex

Abstract A new metallic chromium complex with asymmetric salen ligand and ancillary chloride group (complex 1 ) has been synthesized and applied as co‐catalytic system with bis(triphenylphosphine)iminium chloride (PPNCl) for the polymerization of epoxycyclohexane (CHO) and phthalic anhydride (PA). The catalyst loading, polymerization temperature, reaction time and type of co‐catalyst were varied in order to explore the influences on the catalytic activity of 1 . It was found that 1 exhibited relatively good activity in the catalytic copolymerization of PA and CHO to form the product with more than 90% ester linkage content under mild conditions after the addition of the PPNCl co‐catalyst. This was in sharp contrast to the dinuclear [ONSO]CrCl analogue, where the resulting polymer with more than 97% ether units was achieved under identical conditions. According to the kinetic data, the apparent activation energy of CHO ring‐opening copolymerization was 9.0 kJ mol −1 . A reasonable polymerization mechanism was proposed based on the interaction between the single‐metal two‐component catalyst system and the monomer. © 2020 Society of Chemical Industry