Advances in the Use of Stopped-flow Techniques for Olefin Polymerization

Abstract

The stopped-flow method, by which a reaction can be conducted within an extremely short period (ca. 0.1 s), has been extensively applied to various kinds of investigations of olefin polymerization using Ziegler catalysts. The most important studies using this method are related to kinetic investigations of the polymerization. This method seems to be most suitable for the kinetic study of olefin polymerization with Ziegler catalysts, because the quasi-living polymerization stage can be attained, in which the states of the active sites are constant without a time-dependent change, and the chain-transfer reaction can be essentially negligible. For this reason, it is possible to clarify the effects of hydrogen and the co-catalyst, which are significant and indispensable factors that must be taken into account during the olefin polymerization, and for the polymerization behavior in the initial stage. Attention is also focused on the study of the active sites on the catalysts using the stopped-flow method. This can be done because the nature of the active sites just after their formation can be directly reflected in the polymer obtained during the initial polymerization stage. The method has been employed to produce a novel olefin block copolymer by taking advantage of the polymerization within an extremely short period, where the polymerization time is considered to be shorter than the lifetime of the growing polymer chain. In this article, we outline the various investigations related to the stopped-flow method for the polymerization of olefins with Ziegler catalysts.