Polymerization of aniline nanoparticles was carried out in aqueous micellar solutions of surfactants, including anionic (sodium dodecyl sulfate), nonionic (nonyl phenol ethoxylate), and cationic (cetyltrimethyl ammonium bromide) surfactants. The size and morphology of these synthesized PANI nanoparticles strongly depended on the structure of the surfactants used in the formation of micelles, as shown by transmission electron microscopy. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were used in the characterization of the synthesized PANI nanoparticles. The PANI nanoparticles revealed enhanced conductivity compared to conventional bulk PANI. In addition PANIpoly(methyl methacrylate) (PMMA) nanocomposites were synthesized. The results revealed that the PMMA nanoparticles retarded thermal decomposition and enhanced the conductivities compared with pristine PANI nanoparticles. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012