Mechanism of stereoregular polymerization of butadiene by homogeneous Ziegler‐Natta catalysts. II. Effects of the nature of bases and halogens

Abstract

Abstract The effects of the addition of various bases to metal acetylacetonate–diethylaluminum chloride catalyst systems were investigated. Generally speaking, the cis content of polybutadiene decreases as the basicity of bases in a homologous series increases. The effects were more prominent for the cobalt and the titanium catalysts than for the nickel and the vanadium catalysts. The effects of the species of halogens on the microstructure of polybutadiene were also discussed. In conclusion, the decrease of the cis content was ascribed to the decrease of the electron density of d π orbitals of the transition metal atoms.