One-pot terpolymerization of CO2, cyclohexene oxide and maleic anhydride using a highly active heterogeneous double metal cyanide complex catalyst

This paper describes a convenient one-pot terpolymerization of CO2 cyclohexene oxide (CHO) and maim anhydride (MAH) to afford a poly (ester-carbonate) with a low content of ether units (2 9-4 3 mol %) using a highly active Zn-Co(III) double metal cyanide complex (DMCC) catalyst Terpolymerization was carried out in tetrahydrofuran (THF) at 75-90 degrees C and 1 0-40 MPa and no cyclic carbonate was observed in NMR spectra The number-average molecular weight (M-n) of the terpolymer was up to 14 1 kg/mol with a narrow molecular weight distribution of 1 4-1 7 The apparent efficiency of the catalyst was up to 12 7 kg polymer/g Zn representing the highest catalytic activity for terpolymerization of CO2 epoxides and cyclic anhydrides to date THF dramatically inhibited polyether formation in this terpolymerization owing to its nucleophilicity towards the Zn2+ center of Zn-Co (III) DMCC This presents the first example of solvent-assisted selectivity for inhibiting ether units in CO2 polymerization catalyzed by a heterogeneous system Kinetic analyses of MAH/CHO/CO2 terpolymerization (MAH/CHO 0 2) suggested that polyester production was slightly faster than polycarbonate production in the early stage A mechanism for this terpolymerization catalyzed by Zn-Co (III) DMCC catalyst was proposed Moreover addition of small amounts of MAH (MAH/CHO molar ratio <= 0 2) during CO2/CHO copolymerization can improve the thermal properties of the resultant terpolymers (C) 2010 Elsevier Ltd All rights reserved