Ring-opening polymerization of epoxides and ring-opening copolymerization of CO2 with epoxides by a zinc amino-bis(phenolate) catalyst

Abstract

A one-pot synthesis of poly(ether-co-carbonates) catalyzed by an amino-bis(phenolate) zinc catalyst [L]Zn2Et2(THF) 1 (where [H2L] = n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol) has been developed. Ring-opening polymerization (ROP) of cyclohexene oxide (CHO) can be performed by 1 with and without addition of BnOH or PPNCl as co-catalysts. The ROP of CHO can be inhibited by CO2 pressurization, which leads to the formation of polycarbonate blocks, or presence of other epoxides, which leads to the formation of poly(ether-co-carbonate) containing carbonate linkages and ether linkages. Polycarbonate formation was observed at 1 bar CO2 giving 23% carbonate linkages at this pressure. At 20 bar CO2, 92% carbonate formation was achieved in the presence of limonene oxide (LO). Poly(ether-co-carbonates) from mixtures of epoxides could be synthesized by changes in reaction temperatures and pressures.