Morphology and conductivity tuning of polyaniline using short-chain alcohols by heterophase polymerization

Conducting polyaniline (PANI) nanostructures were obtained by heterophase polymerization of aniline monomer using sodium dodecyl sulfate (SDS) as surfactant in presence of the short-chain alcohols: ethanol, propanol, butanol, pentanol, and hexanol as co-surfactants, and ammonium persulfate (APS) as oxidizing agent. The resulting polymers were analyzed by Field Emission, high resolution scanning electron microscopy (FE-HRSEM), UV/Vis, FTIR, cyclic voltammetry, and X-ray diffraction (XRD). It was observed from FE-HRSEM analysis that fiber-like particles were obtained when polymerizing without alcohol and in presence of ethanol, while very big agglomerates were obtained in presence of propanol and butanol; using pentanol as co-surfactant well-defined and spherical nanoparticles were obtained, the presence of hexanol through polymerization gives both spherical agglomerated and needle-like nanostructures. Final conversions were between 50 and 73 %, in the following order: hexanol = pentanol > butanol > thanol > propanol > without alcohol. Conductivities were in the range of 0.81 to 1.1 S/m with the higher value for that synthesized in presence of pentanol. Difference in conductivity of PANI was ascribed to formation of organic acids as a consequence of reaction between alcohols and APS, thus doping in situ PANI.