Polymerization of ethylene to branched polyethylene with silica and Merrifield resin supported nickel(II) catalysts with α-diimine ligands

Silica and Merrifield resin were used as carriers for the support of α-diimine nickel(II) precatalysts for ethylene polymerization. The α-diimine ligands containing allyl were modified by introducing the reactive Si–Cl end-group, allowing their immobilization via a direct reaction of the Si–Cl groups with the silanols on silica surface or the hydroxyls on the ethanolamine-modified Merrifield resin. The resulting supported α-diimine ligands were characterized by analytical and spectroscopic techniques (NMR and FT-IR). The complexation reactions of the supported ligands with NiBr2(dimethylether) (DME) gave rise to supported α-diimine nickel(II) precatalysts. These heterogeneous precatalysts exhibited high activity for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) as a cocatalyst. The molecular weights of the polyethylenes obtained with the supported precatalysts were much higher than those produced with the corresponding homogeneous precatalysts.

α-Diimine nickel(II) complexes have been immobilized on silica and Merrifield resin. The supported catalysts were used for ethylene polymerization in the presence of MMAO, yielding branched polyethylenes with high molecular weight.Figure optionsDownload as PowerPoint slide