Improving the Protection Performance of Waterborne Coatings with a Corrosion Inhibitor Encapsulated in Polyaniline-Modified Halloysite Nanotubes

Abstract

Organic coatings provide an effective way to improve the corrosion resistance of metals. Traditional organic varnishes, however, either contain highly polluting or toxic components or lack self-healing ability. In this article, we report a feasible method of preparing polyaniline-modified halloysite nanotubes (PANI@HNTs). They were loaded with a corrosion inhibitor, benzotriazole (BTA), and were tested as multifunctional anticorrosion additives for environmentally friendly epoxy waterborne coatings. The PANI@HNTs were formed via the in situ polymerization of aniline in the presence of halloysites. The BTA loading was then carried out and reached up to 14.5 wt.%. The BTA retention ability of the PANI@HNTs was significantly improved in comparison to that of pure HNT. Electrochemical impedance spectroscopy (EIS) tests of the coatings immersed in a 3.5 wt.% NaCl solution showed that the barrier and corrosion inhibition effects were enhanced by two to four orders of magnitude with the incorporation of BTA-loaded PANI@HNTs. The salt spray tests on artificially scratched coatings revealed that the surfaces protected by varnishes doped with the BTA-loaded PANI@HNTs exhibited the lowest degree of corrosion compared to the control samples, illustrating the self-healing potential of the modified coatings.