烷氧基金属化合物引发ε-己内酯开环聚合研究

Research on ring-opening polymerization ofε-caprolactone induced by alkoxy metal compound

在反应温度160℃、反应时间7 h条件下,以烷氧基金属化合物(A-17)为活性种引发ε-己内酯开环聚合制备聚ε-己内酯(PCL),利用核磁共振氢谱(1 H-NMR)分析了产物的微观结构,考察了ε-己内酯单体转化率(η)和产物数均相对分子质量(M n)及多分散性指数(PDI)随反应时间的变化,探讨了该条件下的聚合反应动力学及反应机理。结果表明:1 H-NMR表明产物中的聚合物为PCL,产物中有未反应的ε-己内酯;η随着反应时间的延长而升高,反应初期η增长快,反应后期η增长速度降低,反应7 h时η为90.16%;反应时间从5 h延长到6 h,产物PCL的M n从37788增长到54953,PDI从1.55降低到1.31,反应时间延长到7 h时产物PCL的M n降低到53778,PDI上升到1.43;A-17引发ε-己内酯开环聚合反应为一级反应,反应机理为活性阴离子配位聚合。

Poly(ε-caprolactone)(PCL)was prepared by ring-opening polymerization ofε-caprolactone induced by alkoxy metal compound(A-17)as initiating species at a reaction temperature of 160°C and time 7 h.The microstructure of the product was analyzed by hydrogen nuclear resonance spectroscopy(1H-NMR).The changes of theε-caprolactone monomer conversion(η)and the number average relative molecular mass(M n)and polydispersity index(PDI)of the products with the reaction time were investigated.And the polymerization kinetics and mechanism were discussed under given conditions.The results showed that the product polymer was proved to be PCL by 1H-NMR,and there was unreactedε-caprolactone in the product;theηsharply increased at the initial stage of reaction and moderately increased at the later stage of reaction with the extension of reaction time,and theηwas 90.16%at 7 h of reaction;the M n of the product PCL increased from 37788 to 54953 and the PDI decreased from 1.55 to 1.31 when the reaction time was prolonged from 5 h to 6 h,and the M n of the product PCL decreased to 53778 and the PDI increased to 1.43 when the reaction time was prolonged to 7 h;and the ring-opening polymerization ofε-caprolactone induced by A-17 was a first-order reaction,and the reaction mechanism was active anion coordination polymerization.