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Chemoselective terpolymerization can produce polymer materials with diverse compositions and sequential structures, and thus have attracted considerable attention in the field of polymer synthesis. However, the intrinsic complexity of three‐component system also brings great chanllenge, in regard to the reactivity and selectivity of different monomers. Herein, we report the terpolymerization of CO2/epoxide/anhydride by a binary organocatalytic C3N3‐Py‐P3/TEB (triethylborane) system. Both the activity and chemoselectivity were highly dependent upon the molar ratio of C3N3‐Py‐P3 to TEB, and sequence‐controlled poly(ester‐carbonate) copolymers were readily synthesized through one‐pot/one‐step methodology by tuning the stoichiometric ratio of phosphazene/TEB. In particular, C3N3‐Py‐P3/TEB with a molar ratio of 1/0.5 exhibited an unprecedentedly high chemoselectivity for ring‐opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CO2/CHO. Thus, well‐defined triblock polycarbonate‐b‐polyester‐b‐polycarbonate copolymers can be produced from the mixture of CO2, CHO and PA using a bifunctional initiator. With C3N3‐Py‐P3/TEB=1/1, tapered copolymers were obtained, while random copolymers with high content of polycarbonate (PC) were synthesized with further increasing the amount of TEB. The mechanism of the unexpected chemoselectivity was further investigated by DFT calculations. [ABSTRACT FROM AUTHOR]

Organophosphazenes combined with triethylborane (TEB) were selected as binary organocatalyts for the copolymerization of CO2 and epoxides. Both the activity and selectivity were highly dependent on the nature of phosphazenes. 2,4,6‐Tris[tri(1‐pyrrolidinyl)‐iminophosphorane]‐1,3,5‐triazine (C3N3‐Py‐P3) with a relatively low basicity (pKa=26.5 in CD3CN) 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 CO2 and cyclohexene oxide (CHO), and produced CO2‐based polycarbonates (CO2‐PCs) with high molar masses (Mn up to 275.5 kDa) at 1 MPa of CO2 and 80 °C. Surprisingly, this binary catalytic system achieved efficient CO2/CHO copolymerization with TOF up to 95 h−1 at 1 atm pressure and room temperature. [ABSTRACT FROM AUTHOR]

Organophosphazenes combined with triethylborane (TEB) were selected as binary organocatalyts for the copolymerization of CO2 and epoxides. Both the activity and selectivity were highly dependent on the nature of phosphazenes. 2,4,6‐Tris[tri(1‐pyrrolidinyl)‐iminophosphorane]‐1,3,5‐triazine (C3N3‐Py‐P3) with a relatively low basicity (pKa=26.5 in CD3CN) 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 CO2 and cyclohexene oxide (CHO), and produced CO2‐based polycarbonates (CO2‐PCs) with high molar masses (Mn up to 275.5 kDa) at 1 MPa of CO2 and 80 °C. Surprisingly, this binary catalytic system achieved efficient CO2/CHO copolymerization with TOF up to 95 h−1 at 1 atm pressure and room temperature. [ABSTRACT FROM AUTHOR]