Double metal cyanide complexes synthesized by solvent‐free grinding method for copolymerization of CO 2 and propylene oxide

Two active double metal cyanide (DMC) complexes were successfully synthesized by solvent‐free grinding method. Their structures were characterized by FTIR spectrometer and X‐ray diffractometer. The results showed that Complex 1 (double metal cyanide complex with K 3 Fe(CN) 6 and ZnCl 2 ) and Complex 2 (double metal cyanide complex with K 3 Fe(CN) 6 and Zn(CH 3 COO) 2 ) had the same structures, crystal forms, and lower crystallinity as both of them synthesized by conventional solvent‐based methods, respectively. Investigations on grinding conditions indicated that Complex 1 ground 14 min at a high grinding strength could achieve low crystallinity and showed substantially amorphous structures. Two speculated structures of DMC were given. The alternating copolymerization of CO 2 and propylene oxide with Complex 1 as catalyst obtained anticipated poly(propylene carbonate) (PPC) with very high catalytic activity. The PPC produced by optimized Complex 1 has molecular weight ( M n ) up to 98,000 and narrow polydispersity of 1.93 with more than 90% carbonate linkages. Compared with Complex 1 , Complex 2 displayed low catalytic activity but high selectivity mainly due to the electron atmosphere and strong steric hindrance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011