In situ polymerization of hybrid polyethylene-alumina nanocomposites

Polythylene alumina nanocomposites were prepared using in situ polymerization. Alumina nanomers were prepared by treating alumina nanoparticles with an alkylaluminium compound and a vinyl alcohol. This approach led to (a) grafting double bonds onto the alumina surface and (b) dispersion of alumina nanoparticles in toluene minimizing aggregation. The level of dispersion of nanomers was a function of the molar ratio between the alkylaluminium compound and the vinyl alcohol. Copolymerization of ethylene and nanomers catalysed by the coordination catalyst (diimine) NiCl2/MAO produced hybrid nanocomposites with polyethylene chains covalently bonded to the surface of alumina nanoparticles. Using excess of vinyl alcohol produced crosslinked material. Appropriate preparation of nanomers has produced a good dispersion of alumina nanoparticles in the polythylene matrix. At certain compositions the final material had better mechanical properties, such as yield strength and toughness, than the homopolyethylene.