Corrosion behavior of polypyrrole coating doped by dodecylbenzenesulfonate for mild steel in acidic media

This paper describes the electrochemical synthesis of a dodecylbenzenesulfonate doped polypyrrole (PPy-DBS) coating on a passivated mild steel (MS) and investigation of its corrosion protection behaviors. This coating was prepared by cyclic voltammetry technique and characterized by Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM). The corrosion protection features of the PPy-DBS coated MS were studied in different acid media (0.5 mol L−1 H2SO4 and 0.5 mol L−1 HCl solutions) using linear potentiodynamic polarization, electrochemical frequency modulation and, electrochemical impedance spectroscopy methods. Electrochemical measurements and FESEM images reveal that the PPy-DBS coating presents effective protection for the MS against corrosive species. This may be ascribed to the barrier effect of the polymer coating and utilization of the dodecylbenzenesulfonate dopant with large size during the electropolymerization process.