Synthesis of Diverse Polycarbonates by Organocatalytic Copolymerization of CO2 and Epoxides: From High Pressure and Temperature to Ambient Conditions

Abstract Organophosphazenes combined with triethylborane (TEB) were selected as binary organocatalyts for the copolymerization of CO 2 and epoxides. Both the activity and selectivity were highly dependent on the nature of phosphazenes. 2,4,6‐Tristri(1‐pyrrolidinyl)‐iminophosphorane‐1,3,5‐triazine (C 3 N 3 ‐Py‐P 3 ) with a relatively low basicity (p K a =26.5 in CD 3 CN) and a bulky molecular size ( φ =1.3 nm) exhibited an unprecedented efficiency (TON up to 12240) and selectivity (>99 % polymer selectivity and >99 % carbonate linkages) toward copolymerization of CO 2 and cyclohexene oxide (CHO), and produced CO 2 ‐based polycarbonates (CO 2 ‐PCs) with high molar masses ( M n up to 275.5 kDa) at 1 MPa of CO 2 and 80 °C. Surprisingly, this binary catalytic system achieved efficient CO 2 /CHO copolymerization with TOF up to 95 h −1 at 1 atm pressure and room temperature.