非MAO的茂钛均相催化体系催化苯乙烯间规聚合——[Cp~*TiMe_3]/[Ph_3C]~+[B(C_6F_5)_4]~-催化体系

非ＭＡＯ的茂钛均相催化体系催化苯乙烯间规聚合———［ＣｐＴｉＭｅ３］／［Ｐｈ３Ｃ］＋［Ｂ（Ｃ６Ｆ５）４］－催化体系许光学林尚安（中山大学高分子研究所广州５１０２７５）关键词茂钛络合物，茂金属催化剂，苯乙烯，间规聚苯乙烯间规聚苯乙烯（ｓＰＳ）由于具...

ALUMINOXANE FREE TITANOCENE CATALYSTS FOR SYNDIOTACTIC SPECIFIC POLYMERIZATION OF STYRENE ——[Cp TiMe 3]/ +[B(C 6F 5) 4] - CATALYST SYSTEM

Highly active syndiotactic specific catalyst for the polymerization of styrene are obtained by mixing Cp TiMe 3 with +B(C 6F 5) 4] - in the mole ratio 1∶1,producing 97 5% syndiotactic PS at an activity of 1 15×10 6 gPS/molTi·h.Treatment of Cp TiMe 3] with +B(C 6F 5) 4] - results in the formation of Cp TiMe 2] +B(C 6F 5) 4] - complex,which is a good source in solution of the cationic species Cp TiMe 2] +.Both activity and syndiospecificity of the “cationic” catalyst are no less than the CpTi(OBu) 3/MAO and CpTi(OPh) 3/MAO catalysts,but are much more active than Cp TiMe 3/MAO as well as Cp TiCl 3/MAO.The cationic catalyst is a very effective catalyst precursor for the Ziegler Natta polymerization of styrene to syndiotactic polystyrene at temperatures≥-10℃,while the “cationic” contributes to promoting the polymerization of styrene to atactic polystyrene at temperatures≤-20℃.The molecular weight ( M W ) of sPS increases with the decrease of the temperature,suggesting that lower temperature contributes to reducing the chain transfer and increasing the life of the active species for chain propagation.The T m of the sPS polymerized at -10～70℃ is almost constant.The styrene polymerization behaviors were essentially insensitive to the dielectric constant of the polymerization medium.