预聚温度为40℃ ;主催化剂的浓度为 6.67×10-4 mol L ;铝钛摩尔比为200.共聚反应的催化效率随预聚时间的延长而降低;嵌段共聚物中苯乙烯链节含量随苯乙烯的浓度的增加而增加;外加TIBA对嵌段共聚物的形成及催化效率的提高起关键性作用.
Abstract
The block copolymerization of styrene and ethylene was carried out using a novel catalytic system of η5-pentamethylcyclopentadienyltribenzyloxy titanuim [Cp* Ti(OBz)3] and modified methylaluminoxane (mMAO).The influence of prepolymerization temperature
time
Ti concentration
Al(mMAO)/Ti molar ratio
styrene concentration and the amount of external addition of triisobutylaluminum (TIBA) on copolymerization were investigated in detail. It seems that the conditions of prepolymerization temperature at 40℃
Ti concentration 6.67×10-4 mol/L and Al-(mMAO)/Ti molar ratio 200 are favorable for block copolymerization of styrene and ethylene.The content of sPS segment in copolymer increases with increasing styrene concentration
but the catalytic efficiency decreased with increasing prepolymerization time.External addition of TIBA has an important effect on the formation of block copolymer and enhancing of catalytic efficiency.