METALLOCENE CATALYSTS FOR SYNDIOSPECIFIC POLYMERIZATION OF STYRENE

Syndiotactic polystyrene was synthesised with metallocene catalysts ac tivated by methylaluminoxane (MAO) and trimethylaluminum (TMA). The ca talytic efficiency(C. E.) for syndiospecific styrene polymerization wa s compared with different eta(5)-cyclopentadienyltrialkoxy titanium [C pTi(OR)(3)]. eta(5)-Cyclopentadienyltripropoxy titanium [CpTi(O-n-Pr)( 3)]/MAO/TMA catalyst has a exceedingly high value of C. E. = 4 X 10(4) g PS . (g Ti)(-1). The catalytic efficiency of the catalyst and the m olecular weight and syndiospecificity of polystyrene were affected by catalyst composition and concentration, monomer concentration, polymer ization temperature and time. The optium conditions of polymerization of styrene for [CpTi(O-n-Pr)(3)]/MAO/TMA catalyst are Al/Ti(molar rati o) = 1 000, temperature about 60 degrees C, high styrene concentration (> 2.4 mol/L) and c(Ti) = 0.14 mmol/L for maximum activity or c(Ti) = 0.18 mmol/L for maximum yield. The sPS was separated from polymerizat ion product by extraction with boiling butanone for 8 h, the yield of sPS over 95%.