A PTFE latex, with particles in the submicrometer size range, was employed as seed in the emulsifier-free emulsion copolymerization of two mixtures of acrylic and methacrylic comonomers to obtain PTFE-based core-soft shell nanoparticles. Stable latexes were obtained. By appropriately choosing the ratio between the comonomers and the PTFE seed in the reaction mixture, it was possible to obtain particles with various sizes and a narrow size distribution. The shell is swollen in water due to the presence of the ionic methacrylic acid units. A fractionated-type crystallization phenomenon of the PTFE component was observed and is ascribed to the small size of the PTFE material. The low glass transition temperatures of the shell forming materials could permit the preparation of soft matrix nanostructured films by latex deposition and water evaporation.