Copolymerization of carbon dioxide and epoxides with a novel effective Zn-Ni double-metal cyanide complex

A novel double-metal cyanide complex based on Zn[Ni(CN)₄] was prepared and used as a catalyst for the copolymerizations of carbon dioxide and propylene oxide (PO) and carbon dioxide and cyclohexene oxide (CHO). The copolymers were characterized by IR and ¹H-NMR, and the effects of temperature, pressure, solvent, and preparative methods for the catalysts on catalytic activity and composition of the copolymer were investigated. The results show that this novel catalyst exhibited its highest catalytic efficiency at about 500 g/g of Zn[Ni(CN)₄] for PO and CO₂, whereas the catalytic efficiency for CHO and CO₂ was merely between 5.6 and 22.5 g/g of Zn[Ni(CN)₄]. The molar fraction of carbonate linkages for PO-CO₂ and CHO-CO₂ copolymers reached about 0.6 and 0.3, respectively. The results show that a lower temperature and a higher CO₂ pressure were favorable for the incorporation of CO₂ into the copolymer, and the nonpolar solvents were better media for copolymerization. As a complexing agent, glycol ether exhibited better promoting effects on catalytic efficiency among those investigated, but the catalysts prepared by different complexing agents showed no significant differences in the compositions of the copolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008