Enhanced ethylene polymerization of Ni(II) complexes supported on carbon nanotubes

•Task specific nickel(II) complexes were synthesized.•These complexes were covalently immobilized onto the surface of carbon nanotubes.•The corresponding catalytic systems promoted ethylene polymerization.•Beneficial influence of carbon nanotubes on the catalytic activity was evidenced.•Immobilized systems produced higher molecular weight of the polyethylenes.

A series of nickel complexes Ni1–Ni4 containing N-(5,6,7-trihydroquinolin-8-ylidene)aminoaryl ligands was prepared in good yields. The amino group present allowed covalent anchoring of these complexes through an amido link onto the surface of two kinds of multi-walled carbon nanotubes (MWCNTs). XPS analysis evidenced that the molecular structure of these Ni(II) complexes was maintained after grafting. Activated by MAO, these catalytic systems promoted ethylene polymerization. Our studies evidenced the beneficial influence of the MWCNTs since in most cases, heterogeneized systems are more active than the corresponding unsupported catalysts, producing higher molecular weight polymers in which MWCNTs are homogeneously dispersed.

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