Synthesis of functional polyolefins via ring-opening metathesis polymerization of ester-functionalized cyclopentene and its copolymerization with cyclic comonomers

Abstract

In this work, a series of ester-functionalized polyolefins were synthesized via ring-opening metathesis polymerization (ROMP) of alkoxycarbonyl cyclopentene (alkyl = methyl, iso-propyl and tert-butyl) or its ROMP copolymerization with other cyclic olefins (cyclopentene, norbornene, cyclohexene and cyclooctadiene) using a ruthenium-based catalyst, and the produced polymers were characterized by ¹H and ¹³C NMR, GPC and DSC. Under conventional polymerization conditions, a high monomer conversion of around 80% was obtained. The polymers showed a high molecular weight and relatively narrow molecular weight distribution. These ROMP polymers showed different thermal behaviors due to their chain structure variations. The incorporation ratio of methoxycarbonyl cyclopentene (CPM) into the copolymers can be well controlled by changing the comonomer feed ratio. CPM units were randomly incorporated into the copolymer chains. In addition, the pendent tert-butoxycarbonyl groups in the tert-butoxycarbonyl cyclopentene ROMP polymer were transformed into carboxyl groups via hydrolysis, providing polyolefins with regularly distributed carboxyl pendants. The new functional cyclic monomers synthesized in this work can be applied as the sources of functional moieties to prepare novel functional polyolefin materials via metathesis polymerization under mild conditions.