Electrochemical synthesis of dodecylbenzenesulfonate doped polypyrrole coating with anticorrosive property on the mild steel.

In this study, polypyrrole-dodecylbenzenesulfonate (PPy-DBS) coating the electrochemically was prepared on mild steel in oxalic acid solution including sodium dodecylbenzenesulfonate (SDBS). For this aim, firstly mild steel (ST 37) electrode was passivated in 0.3 mol L−1 oxalic acid solution, then the polymer coating was synthesized with cyclic voltammetry method on this surface after addition of pyrrole and SDBS to this solution. The effects of electrochemical synthesis parameters, such as upper potential (0.8 V; 0.9 V; 1.0 V), scan rate (10 mV s−1, 25 mV s−1, 50 mV s−1, 100 mV s−1) and cycle number (5, 10, 20, 50), on the protective behaviors of PPy-DBS films were investigated and the optimum synthesis conditions were determined. PPy-DBS coating was characterized by cyclic voltammetry, FT-IR spectroscopy and SEM methods. Corrosion protection behavior of this polymer-coated mild steel was investigated in 0.5 mol L−1 HCl and 0.5 mol L−1 H2SO4 solutions by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) methods.