Rare Earth Half-Metallocene-Catalyzed Syndiospecific Styrene Polymerization and Styrene-Ethylene Copolymerization

摘要

On activation with 1 equiv of [Ph_3C][B(C_6F_5)4],rare earth bis(alkyl) complex (C_5Me_4SiMe_3)Ln(CH_2SiMe_3)_2(THF) (Ln = Gd-Lu,Y,and Sc) showed an extremely high activity (up to 1.36 x 10~4 kg of sPS/(mol Ln centre dot h)) and syndiospecificity (rrrr > 99%) for the polymerization of styrene at room temperature in toluene.More remarkably,(C_5Me_4SiMe_3)Sc(CH_2SiMe_3)_2(THF) could effect copolymerization of styrene with ethylene to afford styrene-ethylene copolymers with syndiotactic styrene-styrene sequences.The styrene content in the copolymers could be easily controlled by changing the comonomer feed ratio to reach up to 91 mol%.