Copolymerization of Ethylene and Isoprene by a Ziegler Type Catalyst

Abstract

In the copolymerization reaction the reactivity of the Ziegler type catalyst prepared in the presence of two monomers was controlled by the more reactive monomer. In the case of ethylene-isoprene copolymerization it was found that the presence of a small amount of more reactive ethylene in large amount of less reactive isoprene scarcely affected the catalytic activity. The two kinds of copolymers were obtained, one of which was exclusively consisted of isoprene and the other of both isoprene and ethylene. By infrared spectrum analysis, it was found that the copolymer obtained was to be a block copolymer, and contained more 3, 4 additions of isoprene than that in the homopolymer obtained in the same polymerization condition.
From these results, the followings are concluded. The kind of monomer which added to the end of the glowing polymer chain is controlled by the monomer unit of the growing end. Two or more kinds of active site are presented in this catalyst system.