The sequential block copolymerization products of styrene and ethylene calalyzed by mono-titanocene catalyst η5-pentamethylcyclopentadienyltribenzyloxy titanium [Cp* Ti(OBz)3] and modified methylaluminoxane (mMAO) were fractionated by successive extraction with boiling butanone

THF and chloroform solvents．The isolated block copolymers (22.8 wt％～38.2 wt％ in total)

chiefly existing in THF and chloroform soluble fractions

were characterized by 13C-NMR

WAXD

DSC and GPC methods．The 13C-NMR spectrum of copolymers showed a special structure which composed of sPS segments and branching PE segments．The WAXD pattern of copolymers displayed low crystallinity of both segments．There are long sPS segments and short PE segments in the block copolymers

which showed single sPS melt peak in DSC curves．GPC curves indicated the block copolymerization of styrene and ethylene with mono-titanocene catalytic system has single active spices character．A block copolymerization mechanism of styrene and ethylene with Cp* Ti (OBz)3/mMAO catalyst was proposed．