Electrodeposition of poly(N-methylpyrrole) on stainless steel in the presence of sodium dodecylsulfate and its corrosion performance

• Poly(N-methylpyrrole)-dodecylsulfate coating was synthesized on stainless steel.
• This coating on stainless steel exhibited good protection against corrosion.
• The dodecylsulfate dopant enhanced the corrosion protection of poly(N-methylpyrrole).

Poly(N-methylpyrrole)-dodecylsulfate (PNMPy-DS) coating was electrosynthesized by potentiodynamic method on a stainless steel in oxalic acid solution containing sodium dodecylsulfate for the first time. The effects of electrochemical synthesis parameters, such as applied potential, scan rate and cycle number, on the protective behaviors of PNMPy-DS films were investigated and the optimum synthesis conditions were determined. The PNMPy-DS coating was characterized by the cyclic voltammetry, FT-IR spectroscopy and SEM methods. Corrosion protection behavior of this polymer-coated steel was investigated in 0.5 mol L−1 HCl solution by potentiodynamic polarization and EIS methods. The results show that the PNMPy-DS coating provides effective protection for the stainless steel against to corrosion due to the fact that the large negatively charged dodecylsulfate dopant in the polymer structure electrostatically repels corrosive chloride ions and delays their access to metal surface.