Preparation of Polyaniline Nanoparticles in Micellar Solutions as Polymerization Medium

Chemical oxidative polymerization of aniline was studied in a conventional aqueous solution and in micellar solutions of sodium dodecyl sulfate (SDS, anionic surfactant) and nonylphenol ethoxylate(9) (NP-9, nonionic surfactant) to investigate the effect of molecular structure of surfactants on the polymerization kinetics and particle size. The polymerization kinetics in NP-9 micellar solution were very slow, and this result was explained based on the structural characteristics of surfactant. SDS micellar solutions resulted in a highly transparent solution without any precipitates, whereas some precipitates were visually observed in the NP-9 micellar solution after the reaction finished. The electrical conductivities of polyaniline pellets formed with particles prepared in SDS and NP-9 micellar solutions and aqueous solution showed about 20, 4, and 4 S/cm, respectively. The highest electrical conductivity of particles from SDS micellar solution might be due to the smallest size of particles and the highest doping level of polyaniline.