Synthesis of PE Wax by Chromium Complexes Bearing NP Ligands

摘要

Three binuclear chromium complexes stabilized by 1,5,9,13-tetra(phosphinoamine)cyclohexadecane ligand were synthesized and characterized. In combination with TMA-depleted methylalumoxane/triethylaluminium (DMAO/TEA) as cocatalyst, they generate active catalytic systems for ethylene polymerization to form ultra low molecular weight polyethylene (PE) wax with moderate catalytic activity in methylcyclohexane (MeCy). The molecular weight of PE wax is ranging from 612 to 841 g/mol with a narrow polydispersity (PD = 1.37-1.80). The effects of polymerization parameters, such as solvent, temperature, catalyst concentration, the ratio of cocatalyst on the catalytic activity and properties of the PE wax were also investigated.