Novel P,O-chelated Ni(II) catalysts for ethylene and alpha-olefins polymerization have been used for the copolymerization of ethylene with various long-chain alpha-olefins in emulsion. Nonfunctionalized alpha-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 alpha,-dienes, alpha-olefins bearing a polar functionality in the omega-position, and styrene have also been copolymerized in emulsion. Polymers and latexes have been characterized by an array of techniques including C-13 NMR, TEM, DSC, and GPC. It is shown that this emulsion process is specially adapted for copolymerization of ethylene with polar olefins.