The stereospecifie block copolymer of styrene and 1-butene i．e．sPS-b-PB was synthesized with η5-pentamethylcyclopentedienyltribenzyloxidetitanium(Cp*Ti (OBz)3)／modified methylaluminoxane(mMAO) catalyst．The effects of externaltriisobutylaluminium(TIBA)

prepolymerizationtime of 1-butene and concentration of styrene on catalytic activity and molecular weight were investigated．The catalyticactivity of copolymerization increases and then decreases with successive increasing concentration of external TIBA．and exhibited the highest value of 12．2kgP／gTih at[TIBA]=26 mmol／L．As increasing concentration of styrene

the catalytic activity increases at first and then level off．But it decayed with prolonging prepolymerization time．Molecular weight of the polymers obtained decreases with increasing concentration of external TIBA

but it is weak relative to prepolymerization time．Those copolymerization products obtained were extracted successively with various solvents to separate the existed homo-and co-polymers The block copolymer of sPS-b-PB are soluble either in boiling tetrahydrofuran or boiling chloroform．It accountedfor 21.0％--41.3％ of the total weight of copolymerization products．The weight percent of 1-butene segments of the block copolymer was in the range of 18.7mol％～41.7mol％.The block copolymer was characterized and confirmed by 13C-NMR

FTIR

DSC

WAXD and GPC methods.