Abstract
A series of double metal cyanide (DMC) complex catalysts were prepared in two different methods by using β-cyclodextrin, PEG-1000 and Tween-60 as an additional complex ligands respectively. It was showed that a mixture of crystalline and amorphous DMC was synthesized by using traditional method in which the additional complex ligand was added after the precipitation of DMC. Amorphous and dispersed DMC with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction. The effect of additional complex ligand and preparation method on the crystalline state and catalytic property of DMC were also investigated.
Highlights
Double metal cyanide complex catalysts are known to be extremely useful and active catalysts for the ringopening polymerization of heterocyclic monomers such as epoxides
Amorphous and dispersed double metal cyanide (DMC) with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction
The XRD pattern and the elemental composition are consistent with the results of US Patent 5,952,261 [7]. ß-cyclodextrin was used as additional complex ligand in US Patent 6,204,357 [6], but the effect on the crystalline state and property of DMC catalyst has not been fully discussed
Summary
Double metal cyanide complex catalysts are known to be extremely useful and active catalysts for the ringopening polymerization of heterocyclic monomers such as epoxides. Active catalysts could be prepared in the presence of a low molecular weight complexing agent such as alcohols or esters as an organic coordination ligand[3,4]. This active catalysts are mixture of crystalline (about 35-70 wt%) and amorphous DMC. It is reported[5,6] that catalysts with higher catalytic activity could be obtained by adding additional complex ligand such as PEG-1000 orß-cyclodextrin after DMC were formed. Amorphous and dispersed DMC with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction. The effect of additional complex ligand and preparation method on the crystalline state and catalytic property of DMC were investigated
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