Poly(butyl icrylate-methyl methacrylate)[P(BA-MMAJ/polyaniline (PANI) core-shell complex particles were synthesized with a two-step emulsion polymerization method with P(BA-MMA) as the core and PANI as the shell. The first step was to prepare P(BA-MMA) latex particles as the core via soapless emulsion polymerization. The second step was to prepare P(BA-MMA)/PANI core-shell particles. Sodium dodecyl sulfate was fed into the P(BA-MMA) emulsion as a surfactant, and this was followed by the addition of the aniline monomer. A bilayer structure of the surfactant over the surfaces of the core particles was desired so that the aniline monomer could be attracted near the outer surface of the core particles. In some cases, dodecyl benzene sulfonic acid was added after 2 h when the polymerization of aniline was started. The final product was the desired core-shell particles. The morphology of P(BA-MMA) and P(BA-MMA)/PANI particles was observed with transmission electron microscopy. The thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. Furthermore, conductive films made from the core-shell latexes were prepared, and the electrical conductivities of the films were studied. (c) 2007 Wiley Periodicals, Inc.