Pare earth metal-initiated living polymerizations of polar and nonpolar monomers

摘要

A nonmetallocene-type rare earth metal complex, [(SiMe_3)_3C]_2Yb, was found to proceed the isotactic polymeriza- tion of methyl methacrylate (MMA) to give a high molecular weight polymer with narrow molecular weight distribution. We can synthesize stereo-complexes of poly(MMA) by mixing the resulting isotactic polymer with the high molecular weight syndiotactic poly(MMA) synthesized with SmH(C_5Me_5)_2. Half-sandwich type rare earth metal complex, (C_5Me_5)La[CH(SiMe_3)_2]_2, proceeds the polymerization of styrene, alkyl isocyanates, acrylonitrile, and ethylene.