Corrosion protective poly(aniline-co-o-anisidine) coatings on mild steel

Abstract

Syntheses of corrosion protective poly(aniline-co-o-anisidine) (PAOA) coatings were carried out on mild steel by the electrochemical copolymerization of aniline with o-anisidine under cyclic voltammetry conditions. An aqueous salicylate solution was used as the supporting electrolyte for the synthesis of PAOA coatings on mild steel. These coatings were characterized with cyclic voltammetry, ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and scanning electron microscopy. The FTIR and 1H-NMR spectroscopy studies reveal that during copolymerization of aniline and o-anisidine, there are more o-anisidine units than aniline units in PAOA copolymer. The corrosion protection offered by PAOA coatings to mild steel was investigated in aqueous 3% NaCl solutions using the potentiodynamic polarization technique. The results of the potentiodynamic polarization measurements showed that the PAOA coatings provided more effective corrosion protection to mild steel than the respective homopolymers. The corrosion rate was observed to be dependent on the feed ratio of o-anisidine used for synthesis of the copolymer coatings.