High Active α-Diimine Nickel(II)/DEAC Catalyst System for Ethylene Polymerization

A new tert-butyl-substituted a-diimine compound 1 and its corresponding Ni(II) complex, Ibis {N,N'-(4-tert-butyl-2,6-dimethylphenyl]acenaphthene}dibromonickel (2), were successfully synthesized and characterized by (1)H NMR, (13)C NMR, elemental analysis, FT-IR and XPS. Complex 2 with sterically bulky, donating group tert-butyl, activated by diethylaluminum chloride (DEAC) produces very active catalyst system for the polymerization of ethylene [3.15 X 10(8) g PE/(mol.Ni.h.MPa)] and led to a branched polyethylene (ca. 131 branches/1000 C). The effects of the Al/Ni molar ratio, polymerization temperature and polymerization time on the catalyst activity also were investigated. The catalyst system 2/DEAC showed the highest activity with the 600 of Al/Ni molar ratio at 5 degrees C. The polyethylene (PE) samples were characterized by (1)H NMR, GPC, DSC and TG.