离子液体中氯化稀土催化ε-己内酯开环聚合

Ring-Opening Polymerization of ε-Caprolactone Catalyzed by Rare Earth Chlorides in Ionic Liquid

在离子液体中进行了无水氯化稀土催化ε己内酯(εCL)的开环聚合,并考察了不同氯化稀土、环氧化物、环氧化物/氯化稀土摩尔比、单体浓度、单体/氯化稀土摩尔比、反应温度和时间对聚合的影响.结果表明,无水氯化稀土/环氧化物能有效地催化ε己内酯在离子液体中进行开环聚合,GdCl3和ErCl3的催化活性比其他稀土氯化物高.当温度为60℃,环氧丙烷/ErCl3的摩尔比为30时,εCL在离子液体[bmim]BF4中聚合30min,单体的转化率可达到96.0%,粘均分子量(Mv)为2.54×104.分别采用NMR和示差扫描量热对聚合物的结构和热性能进行了表征.结果表明,εCL在离子液体中发生了酰氧键断裂,聚合的机理是配位插入机理.

Ring-opening polymerization of ε-caprolactone （ε-CL） in the [bmim]BF4 ionic liquid was carried out using LnCl3/epoxide as catalyst, The results show that LnCl3/epoxide can effectively catalyze the polymerization of ε-CL in ionic liquids. The effects of different rare earth chlorides, epoxides, molar ratio of epoxide/LnCl3, monomer concentration, molar ratio of ε-CL/LnCl3, polymerization temperature and time on the polymerization of ε-CL were investigated. When the molar ratio of propylene oxide/ErCl3 is 30, polymerized e caprolactone （PCL） with a viscosity molecular weight of 2.54×10^4 and the conversion of 96.0% can be obtained under the conditions of 60℃ and 30min. Moreover, the catalytic activity of GdCl3 and ErCl3 is higher than that of the other rare earth chlorides. The structure and thermal properties of PCL were characterized by using NMR and differential scanning calorimetry, respectively. The results showed that ε-CL polymerization proceeds according to the coordination-insertion mechanism with a selective cleavage of the acyl-oxygen bond of the monomer,