新型Cp'Ti(O-C_6H_4-X)_3茂钛催化剂的苯乙烯间规本体聚合研究

NEW HIGHLY ACTIVE CATALYSTS Cp'Ti(O-C_6H_4-X)_3 FOR BULK SYNDIOSPECIFIC POLYMERIZATION OF STYRENE

对位卤代的苯酚与五甲基茂三氯化钛在三乙胺存在下进行酯化反应 ,制得五甲基茂基三 (对 卤代苯氧基 )钛的 4种新型化合物Cp Ti(O C6 H4 X) 3(X =F ,Cl,Br,I) .用作主催化剂经甲基铝氧烷 (MAO)和三异丁基铝 (TIBA)活化 ,对苯乙烯间规聚合显示出极高的催化活性 ,催化剂热稳定性好 ,制得的聚苯乙烯间规度、分子量和熔点均高 ,在MAO TIBA Ti =4 0 0 2 0 0 1(摩尔比 ) ,温度 6 0℃时 ,10min催化效率可达 3 4 7× 10 6gPS mol·Ti,MAO TIBA Ti=4 0 0 2 0 0 1时茂钛化合物的催化活性几乎是MAO Ti=6 0 0时的 10倍以上 ;4种茂钛催化剂的活性次序Cp Ti(O C6 H4 F) 3 >Cp Ti(O C6 H4 Cl) 3 >Cp Ti(O C6 H4 Br) 3 >Cp Ti(O C6 H4 I) 3 .

Four kinds of ancillary ligands O C 6H 4 X \[ X(p)=F, Cl,Br,I\] were introduced in the design of novel monotitanocene catalysts,Cp * Ti (O C 6H 4 X) 3 .All of the new catalysts show high activity for styrene sy ndiotact ic polymerization.The catalytic activity of the four monotitanocene increase d in the order:Cp *Ti(O C 6H 4 I) 3 <Cp * Ti (O C 6H 4 Br) 3 <Cp * Ti(O C 6H 4 Cl) 3 <Cp *Ti(O C 6H 4 F) 3.The addition of triisobutylaluminium(TIBA) to the catalyst syst em cause d a dramatic increase of s PS yield .At 90℃,MAO/TIBA/Ti=400/200/1(molar ra t io),the catalytic efficiency of Cp *Ti(O C 6H 4 F) 3 is up to 3.46×10 6 g polymer/m ol·Ti·10 min.The polymerization activity of Cp *Ti(O C 6H 4 X) 3 at MAO/ TIBA/Ti=400/ 200/1(molar ratio) is about 10 times higher than that at MAO/Ti=600(in the absen ce of TIBA).The catalytic efficiency of the catalyst and the molecular weight were affected by catalyst composition,monomer concentration and polymerizatio n temperature.The kinetics of styrene syndiotactic polymerization in toluene was also studied.