Polymerization of Polar Monomers

Abstract

This chapter reviews recent progress in the coordination polymerization of vinyl monomers bearing polar functional groups and their copolymerization with ethylene. Sm and Zr complexes with cyclopentadienyl ligands catalyze the production of poly(methyl methacrylate) (PMMA) from methyl methacrylate (MMA) as well as a block copolymer of ethylene with MMA. The structure of PMMA is controlled to be syndiotactic by chain-end control. Pd complexes with diimine ligands catalyze the copolymerization of ethylene with methyl acrylate (MA); the resulting polymer contains the MA unit as a terminal group of some of the polymer branches. Neutral Pd complexes with chelating monoanionic phosphine-sulfonate ligand enable the copolymerization of ethylene with various vinyl monomers with polar functional groups. The copolymerization of ethylene with methyl acrylate (MA) catalyzed by a Pd/phosphine-sulfonate complex produces a random copolymer that contains MA monomer units at various densities (up to 52 %) in the main chain. Experimental and theoretical approaches to elucidating the polymerization mechanism revealed details of the polymer growth. The catalyst can be used for the copolymerization of ethylene with other polar monomers such as vinyl acetate, allyl acetate, and acrylonitrile, as well as for the alternating copolymerization of vinyl monomers with CO. A bisphosphine monoxide (BPMO) ligand was found to work as a substitute for phosphine-sulfonate.