Electropolymerization and corrosion protection of polyaniline and its copolymer on carbon steel

Purpose - This paper aims to investigate the protection efficiency of a thin film of electrochemically synthesized conducting polymers, such as poly m-toluidine, poly N-methyl aniline, and its copolymer, poly (aniline-co-N-methyl aniline) (PANINMA), on plain carbon steel in 0.1 M HCl. It also attempts to compare the protection efficiency of these compounds with polyaniline (PANI)-coated carbon steel. Design/methodology/approach - The green coloured and adherent coatings were obtained by cyclic voltammetry during sequential scanning of the potential region between - 0.6 and 1.6 V at a scan rate of 10 mVs(-1). Potentiodynamic polarization measurement (DC) was used to obtain an estimate of the corrosion rate and protection efficiency for these electrodeposited polymers on the carbon steel. Scanning electron micrographs (SEM) also were obtained to characterize the deposited coatings. Findings - It was observed that these polymer coatings showed better protection efficiency than the PANI coating. Of the compounds studied, the copolymer PANINMA coating showed higher protection efficiency than other coatings. The SEM observations revealed that the compact continuous dense morphology of PANINMA provided better protection than other coatings. Originality/value - This paper explains the protection efficiency of the substituted and copolymer coatings of PANI on carbon steel.