Living Copolymerization of Ethylene with Dicyclopentadiene Using Titanium Catalyst: Formation of Well-Defined Polyethylene-block-poly(ethylene-co-dicyclopentadiene)s and Their Transformation into Novel Polyolefin-block-(functional polyolefin)s

摘要

Living olefin polymerization enables consecutive enchainment of monomer units without termination. Therefore, it can be used to prepare precisely controlled polymers with desiredmicrostructures such as monodisperse polymers, end-functionalized polymers, and block copolymers, all of which are expected to display new or enhanced properties and thus expanded utilities.1 Recently, it has been reported that several transitionmetal catalysts can mediate the living coordination polymerization of ethylene, propylene, higher R-olefins, R,ω-nonconjugated dienes, and cyclic olefins.2,3 However, the syntheses of the ordered copolymers which have either block or alternating sequences, or functional diblock structures, are remaining challenges in transition metal catalyzed living coordination polymerization. Novel polyolefin chain architectures, such as diblock copolymers with semicrystalline PE block and amorphous poly(ethylene-alt-cyclic olefin) block, have tremendous potential in various applications since their special properties resulted from their unique structure features.Developing functionalized polyolefin block copolymers containing covalently connected polyolefin and functional polymer blocks is one of extremely attractive recent interests in the living coordination polymerization field.4 Chung’s “reactive polyolefin intermediate” approach has been proved as an effective and facile method of functionalization of polyolefins.4b Therefore, the combination of this approach with the living coordination polymerization will be a great breakthrough in the preparation of precisely controlled block copolymers and the well-defined functionalized block polyolefin.