Polymeric catalyst with polymerization-enhanced Lewis acidity for CO2-based copolymers

Ring-opening copolymerization of CO2 and epoxides is a promising way to manufacture high value-added materials. Despite a variety of catalyst systems have been reported, the reaction is still limited by low activity and polymer selectivity. Herein, a strategy of polymerization-enhanced Lewis acidity is reported to construct a series of highly efficient polymeric aluminum porphyrin catalysts (PAPCs). The characterization of the coordination equilibrium constant (Keq) showed significantly enhanced Lewis acidity of PAPC (Keq = 18.2 L/mol) compared to the monomeric counterpart (Keq = 6.4 L/mol), accompanied with increased turnover frequency (TOF) from 136 h−1 to 5500 h−1. Through detailed regulation of Lewis acidity, the highly Lewis acidic PAPC-OTs displayed a record high TOF of 30,200 h−1 with polymer selectivity of up to 99%. Herein, a strategy of polymerization-enhanced Lewis acidity is proposed to construct a series of highly efficient polymeric aluminum porphyrin catalysts (PAPCs) for the copolymerization of CO2 and propylene oxide. The highly Lewis acidic PAPC-OTs displayed a record high activity (TOF = 30,200 h−1) with polymer selectivity of 99%. [Display omitted]