The Effect of 2-Mercaptobenzimidazole-Polyaniline-CeO2 Ternary Nanocomposite Addition as a Superior Pigment for Improvement of Corrosion Resistance in Epoxy Coatings

Abstract

The 2-mercaptobenzimidazole-polyaniline-ceria (MBI-PANI-CeO2) ternary nanocomposite synthesized and used as pigment into epoxy (EP) to improve protection properties of coating on mild steel. The MBI-PANI-CeO2 nanocomposite was prepared using layer by layer assembly. Initially, the PANI layer was polymerized on the surface of CeO2 nanoparticles. Then, the MBI inhibitor was adsorbed on PANI with opposite electrostatic charges. The anticorrosive performance of EP coatings was investigated using electrochemical impedance spectroscopy, salt spray test, and scanning electron microscopy by incorporating various amounts (0.5, 1, and 2 wt. %) of the MBI-PANI-CeO2 nanocomposite. The EP coating containing 1 wt. % of nanocomposite showed the highest corrosion resistance and minimum agglomeration. This coating indicated the coating resistance of 19.1 MΩ cm2, which is greater than EP and EP/CeO2 coatings. The EP/MBI-PANI-CeO2 (1 wt. %) coating showed water uptake percentage (2.09 %) about two times lower than EP/CeO2 coatings (4.56 wt. %), indicating appropriate barrier performance of inhibitor incorporated EP.