Synthesis and optimization of composite coatings based on electrical conductive of polyaniline and polyindole for anti-corrosion protection of carbon steel

Document Type : Original Article


1 Department of Chemistry, Faculty of Science, K.N.Toosi University of Technology

2 ّFaculty of Chemistry, K.N. Toosi University of Technology


In this work, electro-conductive polymers including polyaniline and polyindole were used to protect the carbon steel corrosion (carbon steel with the API5LX52 grade). Electropolymerization of composites containing polyaniline and polyindole on carbon steel was performed in an aqueous solution containing oxalic acid by using cyclic voltammetry (CV) method. In this work, water as a solvent was used due to reducing costs and environmentally friendly issue.
Using electrochemical impedance spectroscopy (EIS), it was found that the composite coating provides better protection than polyaniline and polyindole against corrosive materials (in this work, 3.5% NaCl) for carbon steel.
FTIR method was used to identify synthesized samples. FTIR peaks of synthesized polyaniline and polyindole are matched with their respective FTIR index peaks at the references. The resulting index peaks in FTIR of composite coating indicate that the coating contains polyaniline and polyindole.


[1] C. L. Getting, A. J. Heeger, D. J. Pine and Y. Cao, Synth. Met. 74 (1995) 81.
[2] Dominis, A. J., Spinks, G. M., & Wallace, G. G. (2003). Comparison of polyaniline primers prepared with different dopants for corrosion protection of steel. Progress in Organic Coatings, 48(1), 43.
[3] D. Billaud, E. B. Maarouf , E. Hannecart, Materials Research Bulletin, 29 (12), (1994) 1239.
[4] Billaud, D., Humbert, B., Thevenot, L., Thomas, P., & Talbi, H. (2003). Electrochemical properties and Fourier transform-infrared spectroscopic investigations of the redox behaviour of poly(indole-5-carboxylic acid) in LiClO4-acetonitrile solutions. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 59(1), 163.