The synthesis and the characterization of didecyldimethylammonium methacrylate, a new polymerizable surfactant forming reverse micelles in toluene, have been performed. The reverse micelles have been characterized by small-angle X-ray, small-angle neutron, and dynamic quasi-elastic light scattering experiments. These microemulsions have been UV irradiated in the presence of azobis(isobutyronitrile), at various water contents. For the first time, it has been possible to make monodisperse nanosize latexes in the size range of 2-5 nm by reverse micelle polymerization.