TITANOCENE-METHYLALUMINOXANE CATALYSTS FOR COPOLYMERIZATION OF STYRENE AND ETHYLENE - SYNTHESIS AND CHARACTERIZATION OF STYRENE-ETHYLENE COPOLYMERS

摘要

The copolymerization of styrene and ethylene has been performed using a titanocene-based catalytic system of cyclopentadienyltitanium triphenoxide (CpTi(OPh)(3)) and methylaluminoxane (MAO). The catalyst system exhibited a high catalytic activity of 10(4)-10(5) g (mof Ti . h)(-1) and was found to selectively (more than 90 wt %) give an elastoplastic and amorphous styrene-ethylene (S-E) copolymer with a well-defined random/alternating microstructure and a single glass transition (T-g) as thoroughly characterized by solvent fractionation, GPC, C-13 NMk, DSC, and WAXD. Under the reaction conditions employed, up to 54.5 mol % of styrene could be introduced into the copolymer chains. The composition, microstructure, molecular weight of the copolymers, and catalytic activity of the copolymerization are strongly dependent upon the comonomer feed ratio, polymerization temperature (T-p), CpTi(OPh)(3)/MAO mole ratio, and trimethylaluminum (TMA) content or structure in MAO. For 300 less than or equal to Al/Ti<1000, the copolymerization product was essentially the random. S-E copolymer. For 1000