聚苯乙烯微球负载脲催化剂与碱协同催化环内酯的开环聚合

Ring-opening Polymerization of Cyclic Esters Using Recyclable Polystyrene Supported Urea-Base Binary Catalyst

通过环己基异氰酸酯和4-三氟甲基苯异氰酸酯分别与氨基化聚苯乙烯反应,构筑了聚苯乙烯(PS)负载的环己基脲(PS-U_(1))和聚苯乙烯负载的4-三氟甲基苯基脲催化剂(PS-U_(2)).利用PS-U/KOMe二元催化体系协同催化环内酯的开环聚合.结果表明,PS-U/KOMe二元体系可高效催化ε-己内酯(ε-CL)、δ-戊内酯(δ-VL)和L-丙交酯(L-LA)的开环聚合,制备了低催化剂残留且环境友好的聚酯材料;同时实现了PS-U的回收及循环利用.

To solve the catalyst residual problem,a promising strategy is to immobilize active catalyst on the surface of polymer microspheres to make heterogeneous catalyst.Herein,a metal-free approach to the ring-opening polymerization of lactones using recyclable polystyrene supported urea-potassium methoxide binary catalyst system is described.The new heterogeneous catalysts,polystyrene(PS)-supported cyclohexyl urea(PS-U_(1))and polystyrene-supported 4-(trifluoromethye)phenyl urea(PS-U_(2)),were prepared by reactions of amine-functionalized PS microspheres with cyclohexyl isocyanate and 4-(trifluoromethyl)phenyl isocyanate,respectively.It was found that PS-U-potassium methoxide catalytic system exhibited high catalytic activity for ring-opening polymerization(ROP)of lactones,includingε-caprolactone(ε-CL),δ-valerolactone(δ-VL)and rac-lactide(rac-LA).In addition,the heterogeneous PS-U could be easily separated via simple filtration and recycled.It is worth noting that the recycled PS-U catalyst could be reused without significant decrease of catalytic activity.