Synthesis of Processable Polyaniline and its Anticorrosion Performance on 316LN Stainless Steel

Abstract

The soluble polyaniline (PANI) salts were synthesized by chemical-oxidative polymerization of aniline using sodium dodecylbenzene sulfonic acid, camphor sulphonic acid and hydrochloric acid as dopants and ammonium per sulphate (APS) as an oxidant. The synthesized PANI were characterized by X-ray diffraction, scanning electron microscope, Fourier transform-infrared spectroscopy and thermogravimetric analysis. It is found that the yield of PANI, electrical conductivity, solubility and thermal stability varies with the dopants and the stoichiometrics of monomer/dopant ratios. The PANI doped sample follows the solubility order as: PANI–SDBS > PANI–CSA > PANI–HCl. Thermal stability of PANI–CSA is grater than PANI–SDBS and PANI–HCl. XRD pattern shows the higher crystallinity for HCl and CSA doped PANI while SDBS doped PANI shows the poor crystallinity. SEM study revealed the partially crystalline and agglomerated morphology of the polymer. According to the results, the corrosion rate or corrosion current of PANI–SDBS salts coated samples varies with molar ratios of SDBS to aniline and the optimum molar ratio of PANI–SDBS coating to achieve the best anticorrosive performance on 316LN SS is 2.5 mol mol−1.