Catalytic Polymerization of Ethylene in Aqueous Emulsion with a Simple in Situ Catalyst

Catalytic polymerization of ethylene in aqueous emulsion by in situ catalysts based entirely on compounds commercially available from standard chemicals suppliers, namely a chlorinated derivative of 1,4-benzoquinone, triphenylphosphine, and bis(1,5-cyclooctadiene)nickel, is reported. Using miniemulsions of catalyst solutions in a small amount of hydrocarbon solvent for polymerization, stable dispersions of linear semicrystalline polyethylene are obtained. With 2,3,5,6-tetrachloro-1,4-benzoquinone as the quinone component, polyethylenes with molecular weights (Mn up to 3 × 103 g mol-1) clearly exceeding the entanglement limit are accessible. The catalyst is stable in water for hours with productivities of up to 2 × 103 mol(ethylene) mol(Ni)-1 h-1. Productivities and molecular weights are in the same range for conventional polymerization in organic solvents. Polyethylene dispersions with solids contents of up to 28% are obtained. Aqueous dispersions of ethylene/1-butene copolymers with comonomer incorporations of up to 3 mol % (6 wt %) were prepared.