Functionalization of Polypropylene by the Combination of Metallocene Catalysts and Reactive Comonomers

Abstract

This paper summarizes a functionalization approach that can prepare functional PP with desirable molecular structures, including functional groups, microstructures, high molecular weight, and narrow molecular weight and composition distributions. A newly‐developed catalysis technology with several designed “reactive” comonomers to circumvent the inevitable deactivation of the transition metal cationic active site by functional groups in the direct polymerization process has been applied. The reactive comonomers, containing organoborane, benzylic protons (ϕ‐CH3), and styrene moieties exhibit three essential properties, including (a) stability with the active site, (b) solubility in the polymerization media, and (c) versatility for interconversion to desirable functional groups under mild reaction conditions. With proper choice of metallocene catalysts, they resemble to high a‐olefin monomers and can be effectively incorporated into the PP structure. In addition to the interconversion of the incorporated reactive sites to the desirable functional groups in PP copolymers, some reactive sites have been also transformed into “living” radical or anionic initiators to initiate graft‐from polymerization of polar monomers to obtain PP graft copolymers.