Stereocontrol in radical polymerization of acrylic monomers

A clear effect of Lewis acids, such as scandium trifluoromethanesulfonate [Sc(OTf)(3)], on stereocontrol during the radical polymerization of a designed monomer, benzyl (x(methoxy methyl)acrylate was found. This Lewis acid also influenced the stereochemistry in the radical polymerzation of methyl methacrylate giving a less syndiotactic and more isotactic polymer, although many Lewis acids were not effective. A catalytic amount of Lewis acids, such as Y(OTf)(3) and Yb(OTf)(3). also significantly enhanced isotactic-specificity during the radical polymerization of acrylamide and its derivatives. N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide. Obvious solvent and temperature effects on tacticity were observed in these polymerizations, and poly(NIPAM) with >80% triad isotactic content has been obtained in the presence of Lewis acids.