Polytetrafluoroethylene (PTFE) latices with spherical and rod-like particles in the submicrometer size range, were employed as seeds in the emulsifier-free methylmethacrylate (MMA) emulsion polymerization to obtain PTFE-polymethylmethacrylate (PMMA) core-shell nanoparticles. Stable latices were generally obtained. No residual PTFE was found at the end of the reaction. By appropriately choosing the ratio between MMA and PTFE in the reaction mixture, particles with predetermined size and monodisperse or narrow size distribution were prepared. The high structural regularity of the core-shell samples allows the preparation of film with a periodic distribution of the cores thus ultimately leading to a well structured 2D colloidal crystal. A very peculiar crystallization behavior was observed because of the PTFE compartmentalization in the composite. (c) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2928-2937, 2009