Synthesis and characterization of water-dispersible colloidal polyaniline for corrosion inhibition of mild steel in acidic solution

We report the colloidal nanostructure polyaniline which is extremely water-dispersible and easily synthesized chemically from aniline with commonly used handwash solution (SunlightTM) as a stabilizing agent. The dispersion colloids of polyaniline exhibit multiple color changes from orange-yellow to dark-green during the progress of polymerization reaction. The as-synthesized polyaniline polyaniline is highly dispersed in aqueous medium for more than 90 days. The UV-vis spectrum of this polyaniline has shown three prominent peaks at 355 nm, 431 nm and 771nm assigned to π-π* transition in the benzenoid ring, second and third peaks are related to doping and polarons respectively. The anti-corrosion studies of water-dispersible polyaniline adsorbed on mild steel exposed to 0.1M HCl solution were performed by potentiodynamic polarization and electrochemical impedance spectroscopy. It has been found that water-dispersible polyaniline is more efficient inhibitor since it showed higher corrosion inhibition efficiency than the monomer, whereas the monomer alone accelerated the rate of corrosion. The maximum corrosion inhibition efficiency of 92.35% has been evaluated using corrosion current density. © University of Manchester and the authors.