Synthesis of poly(O-anisidine) coatings on low carbon steel by electrochemical polymerization of O-anisidine

Abstract

The poly(O-anisidine) (POA) coatings have been synthesized on low carbon steel (LCS) substrates by electrochemical polymerization (ECP) of O-anisidine. The synthesis of POA coatings was carried out under cyclic voltammetric and galvanostatic conditions from an aqueous solution of oxalic acid. It has been observed that the formation of POA coatings on LCS occurs after the passivation of its surface via the formation of polycrystalline iron oxalate (FeC2O4.2H2O) interphase. The formation of iron oxalate interphase is confirmed by fourier transform infrared spectroscopy, glancing angle x-ray diffraction (GAXRD) measurements and scanning electron microscopy (SEM). Uniform, granular, and strongly adherent dark green POA coatings were obtained on the LCS substrate by ECP of O-anisidine. These coatings were characterized by cyclic voltammetry (CV), potential-time (E-t) curves, UV-visible absorption spectroscopy and SEM. The potential-time curve is characterized by an induction time before the ECP of O-anisidine. The induction time is found to be dependent on the applied current density. The optical absorption spectroscopy study reveals the formation of conducting emeraldine salt phase of POA. Our results reveal that the oxalic acid is a suitable medium for the ECP of O-anisidine on the LCS substrate and it favors the formation of emeraldine salt (ES) phase of POA. © 2002 John Wiley & Sons, Inc. Adv. Polym. Techn.