Synthesis of molecular weight controllable bimodal polyethylene from fluorinated FI–Ti catalyst coupled with ZnEt2

Molecular weight controllable bimodal polyethylene was synthesized by adding ZnEt2 during ethylene living polymerization with the fluorinated FI–Ti catalyst system, bis[N-(3-methylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] TiCl2/dMAO. The presented FI–Ti catalyst system was demonstrated to perform good living feature. High molecular weight polyethylene with narrow polydispersity was obtained in the absence of ZnEt2. ZnEt2 was found to be a useful molecular weight regulator in this catalyst system. Increasing the Zn/Ti ratio led to a monotonic decrease in the molecular weight. The stagewise process allowed for a facile control on the molecular weight of bimodal polyethylene in a wide range: the molecular weight of high fraction could be controlled via altering the living polymerization time, the molecular weight of low fraction could be controlled via varying the Zn/Ti ratio. This method shows a new application for the living coordination polymerization technique.