Double Metal Cyanide Complex Epoxy Alkane Ring - Opening Polymerization Studies

A number of double metal cyanide (DMC) complexes based on Zn3[Co(CN)6]2 were prepared with several different methods. XRD, IR, atom absorption and elemental analysis were used to characterize their chemical composition, morphology and their chemical structure. The effects of ZnCl2, organic ligands and their complexing ways, temperature, shear stirring rate and time on their morphologies in DMC complexes preparation were studied in this paper. The relationship of the morphology and catalytic activity of DMC were also brought forward. And the more important, the roles of excess ZnCl2 and organic ligand in DMC complex or the effects of excess ZnCl2 and organic ligand on the morphology, chemical structure and catalytic activity of DMC complex were illuminated. It showed that excess ZnCl2 in DMC complex was necessary for its high catalytic activity, The typical cubic lattice structure of pure Zn3[Co(CN)6]2 was destroyed with excess ZnCl2 added. The characteristic absorptions of DMC with excess ZnCl2 in IR were shifted in comparison with those of pure Zn3[Co(CN)6]2. A new chemical bond structure of DMC with excess ZnCl2 was developed but not confirmed. We also gave out an explanation of the differences between the new chemical bond structure and the structure of pure Zn3[Co(CN)6]2 and the active point in DMC. Without excess ZnCl2, the organic ligands can not affect any more the morphology of DMC, a typical cubic lattice structure, its chemical bond structure or the catalytic activity of PO polymerization. But if excess ZnCl2 was existed in DMC, many factors indicated at the beginning, including the organic ligand, can clearly affect the morphology and catalytic activity of DMC. Among those factors, organic ligand was the most important matter to influence the morphology of DMC complex. The results showed that the electronegation of atom with affluent electrons and the number of such atoms in organic ligands together influenced the morphologies of DMC complexes. The stronger the electronegation of such atom was, the lower the crystallinity of DMC complex prepared was. It was also proved that the strength of the electronegation of such single atom was more effective than the number of such atoms on the morphology of DMC complex. Further research showed that the only role of organic ligand in DMC preparationwith excess ZnCl2 existed was to control its morphology, then to affect its catalytic activity, but not to affect the chemical structure of DMC. It is not a necessary composition in DMC-catalyzed PO polymerization or a content concerned with the mechanism of ring-opening PO polymerization. Amorphous DMC complex was favorably formed in the reaction system if the organic ligand was existed before precipitation. The proper precipitation reaction temperature was about 30 so that the crystallinity of DMC complex prepared was the lowest. The effect of shear stirring rate on morphology of DMC complex in the preparation reaction was limited when existing organic ligand before precipitation. Another important factor in our research was that the morphology of DMC complex in organic ligand was not stable, it was transforming with time. The last but not the least, we presented the relationship of the morphology of DMC complex and its catalytic activity. In general, the higher the crystallinity of DMC is, the lower its catalytic activity is. Those DMC complexes approaching amorphism were more active to PO polymerization.A number of double metal cyanide (DMC) complexes based on Zn3[Co(CN)6]2 were prepared. A little of a third compound was added to those DMC complexes by two means. The effects of metal cation, anion and metal oxide on the catalytic activity of DMC were studied. The result showed that only ZnSO4 and AlCl3 added by method B) were used to promote the catalytic activity of DMC complex. The others in all had a negative influence on the catalytic activity of DMC complex to some extend. Especially for those salts (MXW) added before precipitation that can be precipitated with [Co(CN)6]3- was the most negativ...