Copolymerization of butadiene with styrene using a rare-earth metal compound-dialkylmagnesium-halohydrocarbon catalytic system

Copolymerizations of butadiene (Bd) with styrene (St) were carried out with catalytic systems composed of a rare-earth compound, Mg(n-Bu)(2) (di-n-butyl magnesium) and halohydrocarbon. Of all the rare earth catalysts examined, Nd(P-507)(3)-Mg(n-Bu)(2)-CHCl3 showed a high activity in the copolymerization under certain conditions: [Bd]=[St]=1.8mol 1(-1), [Nd]=6.0 x 10(-3) mol 1(-1), Mg/Nd=10, Cl/Nd=10 (molar ratio), ageing for 2h, copolymerization at 50degreesC for 6-20h. The copolymer of butadiene and styrene obtained has a relatively high styrene content (10-30 mol%), cis-1,4 content in butadiene unit (85-90%), and molecular weight ([eta]=0.8-1 dL g(-1)). Monomer reactivity ratios were estimated to be r(Bd)=36 and r(St)=0.36 in the copolymerization. (C) 2002 Society of Chemical Industry.