Effects of morphology and composition on catalytic performance of double metal cyanide complex catalyst

Double metal cyanide (DMC) complexes based on Zn-3[Co(CN)(6)](2) were prepared using different zinc salts and complexing agents and They were characterized by elemental analysis, IR and XRD. The catalytic properties of DMC complexes were determined in polymerization of propylene oxide. Great differences in morphology of DMC complexes was were correlated with preparation route as well as with the kind of zinc salts employed. The catalytic activity was strongly dependent on the morphology of DMC complexes and composition of catalysts. The study revealed that the amorphous catalyst made from ZnCl2 and t-BuOH had the highest activity (up to 26 kg polymer/g catalyst). The DMC catalyst was non-stoichiometric. Polymerization of propylene oxide (PO) catalyzed by DMC proceeded in a controlled manner. The molecular weight of each polymer was controlled by the monomer/initiator ratio, the values of molecular weight distribution (MWD) were in the range of 1.23-1.48. The polymer has an atactic structure and a head-to-tail regiosequance. (C) 2002 Elsevier Science B.V. All rights reserved.