三氟甲基磺酸三甲基硅酯/四氯化钛复合体系引发 1, 3-戊二烯的阳离子聚合

研究了以三氟甲基磺酸三甲基硅酯(CH~3)~3SiOSO~2CH~3,TMSOFf]为主引发剂,TiCl~4为共引发剂的复合引发体系对1,3-戊二烯(PD)的聚合行为。TMSOTf/TiCl~4复合体系引发PD不但比单独的TiCl~4引发具有更高的引发活性,而且提高了聚合物分子量,能把聚合反应速率提高8.8倍,把聚合物的收率从TiCl~4引发的62.5%提高到95%以上。对该复合体系聚合PD的动力学,反应机理所作的研究表明:TMSOTf和TMSOTf/TiCl~4都是通过它们与体系中残存水通过水解生成的质子酸引发进行的,聚合反应属一级反应。在该体系中加入酮类后,产率和分子量均降低,但均随着酮类的位阻的增加而增大。

Cationic polymerization of 1, 3-pentadiene initiated by (CH~3) ~3SiOSO~2CF~3/TiCl~4 system

The polymerization of 1,3 - pentadiene initiated by TMSOTf/TiCl4 initiating system is reported.The results showed that, the initiating system has an higher activity than TiCl4 alone. It can increase the molecular weight and raise reaction rate of polymerization. The polymer yield increases with the TMSOTf]/TiCl4 ratio,and then keeps constantly when the TMSOTf]/TiCl4]ratio is not less than 0.5, The molecular weight reaches a maximum when TMSOTf]/TiCl4] = 1. The reaction kinetic and reaction mechanism are studied. In our study, the polymerization of PD is initiated by the TiCl4 in complexation with HOTf released by hydrolysis of TMSOTf. The yield and the molecular weight increase with steric hindrance of kentone.