Syndiotactic polystyrene and atactic polypropene were synthesized with different titanium compounds

in particular of η5 cyclopentadienyltri n propoxy titanium [CpTi(OPrn)3] and modified methylaluminoxane (m-MAO) homogeneous catalytic system.The titanium ligands affect catalytic activity of styrene syndiospecific polymerization and propene polymerization.The effects of the percentage contents of the trimethylaluminum (TMA) coexisted inm-MAO

which can be controlled by changing H2O and TMA molar ratio during the preparation of MAO by partial hydrolysis of TMA with Al2(SO4)3·18H2O

on polymerization of styrene and propene have been studied in detail.The external addition of alkylaluminium(AIR3

trimethylaluminum

triethylaluminum

tri-isobutylalumimum) to CpTi(OPrn)3/m-MAO catalytic systems may also influence both catalytic activity and molecular weights of syndiotactic polystyrene produced.The oxidation states of titanium in different CpTi(OPrn)3/m-MAO catalytic systems were determined by redox titration method.It results that Ti(Ⅲ) is good for styrene syndiospecific polymerization in higher catalytic activity

while Ti(Ⅳ) is good for propene's polymerization.Oxidation state of tinanium in catalyst system does not clearly affect the tacticity of these two kind of polymers obtained.