Radical Polymerizations of Methyl Methacrylate and of Related Monomers with a Ruthenium Complex–Triphenylphosphine Catalyst

Abstract

Methyl methacrylate, methyl acrylatelate, and dimethyl itaconate are polymerized in homogeneous solutions with a catalyst derived from dichloro(dodeca-2,6,10-triene-1,12-diyl)ruthenium(IV) 1 and triphenylphosphine. The polymer yields of these three monomers increase with the increasing molar ratio of triphenylphosphine to 1. 1 itself has stable π-allylic bonds and yields no polymer. With addition of triphenylphosphine to 1, the π-allylic bonds are converted into active σ-allylic ones, which are considered to participate in the initiation of these polymerizations. On the basis of the tacticity of the resulting poly(methyl methacrylate), of the kinetic investigations on the polymerization of methyl methacrylate, and of the composition of methyl methacrylate–styrene copolymer, it is concluded that the polymerization proceeds through a radical mechanism. The mechanism of the formation of the radical species in the initiation is discussed on the ground of the specificity of the activity for the polymerizations of typical vinyl monomers.