Electrochemical synthesis and corrosion behavior of polyaniline-benzoate coating on copper

Electrochemical polymerization of polyaniline (PANI) coating on copper electrode was performed galvanostatically in the current density range between 0.50 and 1.25 mA cm−2, from aqueous solution of 0.3 mol dm−3 sodium benzoate and 0.2 mol dm−3 aniline. The corrosion behavior of PANI coated copper and copper electrode exposed to 0.5 mol dm−3 sodium chloride solution was investigated by potentiodynamic and electrochemical impedance spectroscopy techniques. It was observed that thin PANI (5 μm) coating had provided efficient protection (∼96%) to copper in 0.5 mol dm−3 sodium chloride solution. Unusual initial impedance behavior to that normally observed with conventional organic coatings was attributed to dedoping of benzoate anions from the polymer coating.