Mostafa Khoshsefat - Department of Catalyst, Iran Polymer and Petrochemical Institute (IPPI), P.O. Tehran, Iran
Saeid Ahmadjo - Department of Catalyst, Iran Polymer and Petrochemical Institute (IPPI), P.O. Tehran, Iran
Gholam Hossein Zohuri - Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
Mohammad Mahdi Mortazavi - Department of Catalyst, Iran Polymer and Petrochemical Institute IPPI

To investigate dinuclearity and bridge effects on the catalyst performance and some polyethylene properties, two binuclear and a mononuclear α-diimine Ni(II)-based catalysts were comprised. Diphenyl Bi-Nuclear catalyst (DBNC) with a structure showed the highest activity (1750 g PE/mmolNi. h.) at the same ethylene polymerization condition while the bi-nuclear catalyst (BNC) illustrated moderate activity (1073 g PE/mmolNi. h.) and mono-nuclear catalyst (MNC) with no activity. This observation assigned to synergistic dinuclearity and cooperative effects which increased as the length, flexibility and thermal stability of bridge increased in DBNC (biphenyl methylene spacer). DSC thermograms revealed that polymer resulted using DBNC has insignificant crystallinity degree less than 1% with melting point at 117.2 °C, however, BNC yielded polyethylene with 24.7% crystallinity and Tm=123.0 °C. The vinyl content and branching of resulted PE in presence of catalyst DBNC were 21.2 and 101, however, these quantities decreased to 9.1 and 78 for catalyst BNC, respectively

Binuclear α-diimine complex -Catalytic polymerization -Polyethylene -Dinuclearity-Structure-Property relation