Metallocene catalysts for syndiospecific polymerization of styrene

Syndiotactic polystyrene was synthesised with metallocene catalysts activated by methylaluminoxane (MAO) and trimethylaluminum (TMA). The catalytic efficiency(C. E.) for syndiospecific styrene polymerization was compared with different eta(5)-cyclopentadienyltrialkoxy titanium [CpTi(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 molecular weight and syndiospecificity of polystyrene were affected by catalyst composition and concentration, monomer concentration, polymerization temperature and time. The optium conditions of polymerization of styrene for [CpTi(O-n-Pr)(3)]/MAO/TMA catalyst are Al/Ti(molar ratio) = 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 polymerization product by extraction with boiling butanone for 8 h, the yield of sPS over 95%.