Evaluation of anti-corrosion properties of electrosynthesized polyaniline on copper at various immersion times

Due to the many uses of copper metal and its alloys, great deal attention has done to different methods of corrosion protection in corrosive environments. Using of organic coating is a great way to protect metal from corrosion, especially if the coating also has good mechanical properties. Electrodeposit of conductive polymer on the surface of an electrode is a very wide research in electrochemistry during the last decades. In this research, homogeneous and the adherent polyaniline coating was electrosynthesized on copper metal by using the chronopotentiometery under galvanostatic conditions method. During the formation of polyaniline coatings, three stages (electro-adsorption of monomer and electrolyte and initiation of formation of passive film, growth and impingement of the passive film and decomposition of the latter and formation of polymer coatings) are observed. The synthesized coatings were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and SEM.

The improved corrosion protection effect of polyaniline after 24 hours immersion time in 3.5% NaCl solution was demonstrated by performing a series of electrochemical experiments potentiodynamic and impedance measurements on copper electrode. The effect of applied current density on the protective properties of polyaniline coatings has been investigated, and it was shown that protection efficiency depends on the applied current density. The corrosion current decreases significantly from 43.56 µA cm-2 for blank electrode copper to 0.84 µA cm-2 for the copper that was coated with polyaniline under the same conditions. According to the results, the polyaniline coating enhanced the corrosion protection effect compared to uncoated electrode.