Formation of PANI-PVA salt via H-bonding between PVA and PANI: Aqueous coating for electrostatic discharge, sensor and corrosion applications

Abstract

This work aims to make environmentally friendly coating consists of an aqueous dispersion of conducting polyaniline (PANI) salt containing H2SO4 and PVA dopants in polyvinyl alcohol (PVA) for electrostatic discharge, sensor and corrosion applications. Aniline is oxidized by ammonium persulfate to PANI-sulfate salt (PANI-SA) without using any protic acids, wherein, sulfuric acid generated from ammonium persulfate during the oxidation of aniline gets doped on to PANI system. The results of PANI-SA are compared with (i) PANI-H2SO4 salt prepared in presence of sulfuric acid in the aniline polymerization and (ii) PANI salt containing dopants of H2SO4 and PVA, (PANI-SA-PVA), prepared with polymeric alcohol, PVA, instead of hazardous sulfuric acid, in the polymerization of aniline. Yield, conductivity, density, diffraction pattern, morphology and thermal properties of PANI-SA are more or less similar to that of the PANI-SA-PVA system. However, yield and conductivity of PANI-H2SO4 are higher than that of PANI-SA-PVA due to the increase of oxidizing efficiency by H2SO4. These three salts, PANI-SA, PANI-H2SO4 and PANI-SA-PVA are dissolved in aqueous PVA. These dispersions are coated on (i) glass slide to find the hydrophilic nature (ii) transparent polyethylene terephthalate film for ESD application, (iii) ceramic tube for sensing ammonia gas, and (iv) stainless steel plate for corrosion study. Among the three PANI salts, PANI-SA-PVA dispersed in PVA shows better performance.