Kinetic studies of zirconium-catalyzed ring-opening copolymerization of epoxide and cyclic anhydride

Zirconium(IV) isopropoxide complexes supported by the ligands 2-pyridylamino- N,N-bis(2-methylene-4,6-dimethylphenolate), L1, 2-pyridylamino- N,N-bis(2-methylene-4,6- tert-amylphenolate), L2, and N,N-dimethyl- N,N-bis(2-methylene-4,6-dimethylphenolate)ethylenediamine, L3 (1–3) when combined with cocatalyst, 4-dimethylaminopyridine (DMAP) or bis(triphenylphosphine)iminium chloride, were assessed for the ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO), and phthalic anhydride (PA). Complex 1, when combined with DMAP, resulted in the highest polyester conversions and selectivity demonstrating the best activity for CHO/PA ROCOP. Kinetic studies with complex 1 determined an overall second-order rate law with a first-order dependence in CHO and catalyst concentrations, and a zero-order dependence in PA concentration. Moderate molar mass polymers with narrow dispersities were obtained and the polymers showed decomposition temperatures above 180 °C and glass transition temperatures of 43 °C.