DBU/碘化锂双催化体系催化三亚甲基碳酸酯开环均聚合

Ring-opening polymerization of trimethylene carbonate catalyzed by DBU/lithium iodide dual catalytic system

以1,8-二氮杂二环[5.4.0]十一碳-7-烯(DBU)/碘化锂(LiI)为双催化剂,苯甲醇(BnOH)协同催化单体三亚甲基碳酸酯(TMC)开环均聚合,得到产物聚三亚甲基碳酸酯(PTMC).反应的最优条件为:二氯甲烷为溶剂,[TMC]=1.0 mol·L^(-1),[TMC]/[DBU]/[LiI]/[BnOH]=200∶1∶1∶1,25℃下反应45 min,所得PTMC的产率为97.7%,数均分子量为20.4 kg·mol^(-1),分子量分布为1.19.DSC热分析结果表明,PTMC没有熔融峰和结晶峰,说明PTMC为一种无定形聚合物.利用1HNMR和IR对PTMC结构进行端基分析,并推测聚合机理为“单体-活化”机理.

The ring-opening homopolymerization of trimethylene carbonate(TMC)catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)/lithium iodide(LiI)is systematically studied in coordination with benzyl alcohol(BnOH).The polytrimethylene carbonate(PTMC)is obtained.The optimum condition of the polymerization reaction was as follows:[TMC]=1.0 mol·L^(-1),[TMC]/[DBU]/[LiI]/[BnOH]=200∶1∶1∶1,T=25℃,t=45 min,and dichloromethane as solvent.The yield of PTMC can reach 97.7%.The number average molecular weight of the polymer is 20.4 kg·mol^(-1)and the molecular weight polydispersity is 1.19.The DSC measurement of PTMC displays no melting peak and no crystalline peak and it further shows that PTMC is an amorphous polymer.The structure of PTMC is confirmed by 1HNMR and IR techniques,and the polymerization mechanism is inferred via a“monomer-activated”process.