LIVING POLYMERIZATIONS AND COPOLYMERIZATIONS OF ALKYL ACRYLATES BY THE UNIQUE CATALYSIS OF RARE-EARTH-METAL COMPLEXES

Rare earth metal complexes such as SmMe(C(5)Me(5)2)(THF) or YMe(C(5)Me(5))(2)(THF) (THF = tetrahydrofuran) catalyze the living polymerization of alkyl acrylates (alkyl = methyl (Me), ethyl (Et), n-butyl (nBu), tert-butyl (tBu)) to give high molecular weight polymers, with extremely narrow molecular weight distributions, in high conversion. Random living copolymerization of methyl acrylate with n-butyl acrylate was successful by the effective catalytic action of SmMe(C(5)Me(5))(2)(THF). By taking advantage of the living polymerization of alkyl acrylates and alkyl methacrylates, a triblock copolymer of methyl methacrylate/n-butyl acrylate/methyl methacrylate was prepared, and the resulting polymer exhibited good elastic properties. In particular, an 8:72:20 copolymer had an ultimate elongation of 163% and compression set of 58%. Block copolymerizations of alkyl acrylates with lactones gave lactone rich copolymers with narrow molecular weight distributions.