Heterogeneous catalysts immobilizing α-diimine nickel complexes into fluorotetrasilicic mica interlayers to prepare branched polyethylene from only ethylene

The α-diimine nickel (II) complexes immobilized into the clay mineral interlayer were prepared by the reaction of the Ni2+ ion-exchanged fluorotetrasilicic mica and the α-diimine ligand. These procatalysts showed a high catalytic activity for the slurry polymerization of ethylene in the presence of methylalumoxane, triethylaluminum or triisobutylaluminum. The activity was strongly affected by the solvent used in the preparation and the steric bulk of the ligand. A high activity (2313 kg-PE mol-Ni−1 h−1) was obtained by the polymerization at 50 °C in the presence of triisobutylaluminum using the procatalyst prepared with the [Ar–NC(CH3)C(CH3)N–Ar (Ar = 2,6-C6H3(CH3)2)] ligand in acetonitrile.