Electropolymerization of p-toluene sulfonic acid doped polyaniline on copper and its application as a corrosion inhibitor

Purpose The purpose of this paper is to study the inhibitive effect of p-toluene sulfonic acid (p-TSA) doped polyaniline on corrosion of copper in 0.1 M hydrochloric acid (HCl) solution. Design/methodology/approach The. electrochemical deposition of polyaniline doped with p-TSA on pure copper metal was studied potentiodynamically. The electrochemical study of the working electrode was performed at open-circuit potential, then using potentiodynamic polarization and also with electrochemical impedance spectroscopy in 0.1 M HCl solution. The p-TSA doped polymer deposit was characterized using Fourier transform infrared spectroscopy, with the UV-vis and thermogravimetric analysis/differential scanning calorimetry techniques. The morphology of the deposited polymer was studied by scanning electron microscopy. Findings The results revealed that the p-TSA self-doped polymer had better corrosion inhibition efficiency than did the un-doped polyaniline. It exhibited approximately 88.9 percent inhibition efficiency at 2x10(-3) M concentration of p-TSA, according to charge transfer resistance (R-ct) values evaluated from Nyquist plots. Research limitations/implications The high dissolution tendency of metal surfaces generally occurs before the electropolymerization potential of the monomer is achieved. It was difficult to electrodeposit the conducting organic polymer on the surface of metal. Practical implications Some organic conducting polymers are toxic and hazardous from the environmental viewpoint. The electrochemical deposition of p-TSA doped polyaniline is impractical for larger structures. Originality/value The paper demonstrates that p-TSA doped polyaniline is environmentally benign and can be used for the protection of copper metal as a cathodic inhibitor.