Ethylene polymerization catalyzed by nickel(II) keto-ylide complexes has been performed in water to yield a latex of linear PE. Colloidal stability is highly enhanced by the use of a miniemulsion technique to disperse the catalyst prior contact with the monomer. Latex of typically 200 nm particle diameters and up to 10% solids are generated by this method. The influence of several factors (temperature, pressure, solids) onto the polymerization is studied in detail. The surfactant adsorption isotherms onto these highly crystalline and nonpolar particles are also presented.

A series of highly active nickel-based neutral catalysts for ethylene polymerization is presented. These catalysts are obtained by direct complexation of simple fluorinated ketoylides onto bis(1,5-cyclooctadiene)nickel. Catalyst formation readily occurs in the presence of an olefin, but due to the electron deficiency of the ligand, it hardly happens in the absence of an olefin or another Lewis base. Activities greater than 2 × 106 (gPE/gNi)/h and productivities higher than 15 × 106 gPE/molNi are typically observed. These catalysts are also active for the polymerization of α-olefins such as 1-hexene and 1-propene. Polymer characterization indicates that highly linear, low molecular weight PEHD is formed by these complexes.

Reversible addition-fragmentation chain transfer (RAFT) radical polymerisation enables to synthesise well-defined homopolymers and block copolymers based on 2-(acetoacetoxy)ethyl methacrylate, which are capable to strongly coordinate to metals and metal ions.

Novel P,O-chelated Ni(II) catalysts for ethylene and R-olefins polymerization have been used for the copolymerization of ethylene with various long-chain R-olefins in emulsion. Nonfunctionalized R-olefins have been copolymerized with ethylene using miniemulsion to disperse the catalyst at the nanometric level. The influence of the comonomer on catalyst performances as well as latex properties has been analyzed. High comonomer incorporation and stable latex of 30% solid content can be achieved by this method. Other comonomers such as R,ω-dienes, R-olefins bearing a polar functionality in the ω-position, and styrene have also been copolymerized in emulsion. Polymers and latexes have been characterized by an array of techniques including 13 C NMR, TEM, DSC, and GPC. It is shown that this emulsion process is specially adapted for copolymerization of ethylene with polar olefins.

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