Linear/branched Block Polyethylene Produced by α-Diimine Nickel(Ⅱ) Catalyst and Bis(phenoxy-imine) Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

作者：Ding-Ding Zhao; Yan-Hui Hou; Ke-Ning Zong; Mi-Mi Cui; Bin-Yuan Liu; Min Yang^*

来源：Chinese Journal of Polymer Science, 2021, 39(12): 1581-1589.

In order to promote development of linear/branched block polyethylenes based on new catalytic systems, we synthesized a novel α-diimine nickel(Ⅱ) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures. The activity of α-diimine nickel(Ⅱ) catalyst was 3.02×106 g·molNi-1·h(-1) at 70 °C, and resultant polyethylene possessed 135/1000 C branches. The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(Ⅱ) complex/bis(phenoxyimine) zirconium in the presence of diethyl zinc. With the addition of Zn Et2(from 0 to 400), the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks. The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained via adjusting Zn Et2 equiv. and molar ratio of two catalysts. In addition, the branching degree of the polyethylene increased from 13/1000 C to 56/1000 C with the increase of the proportion of α-diimine nickel(Ⅱ) catalyst.Using this binary catalyst system, the reaction temperature of chain shuttling polymerization can be carried out at 70 °C, which is more conducive to industrial application.

• 单位
  河北工业大学