Nanostructured hollow polyaniline (PANI) capsules are good candidates for encapsulation of corrosion inhibitors and pH-responsive release when incorporated into organic coatings. In previous studies, the corrosion protection performance of PANI capsules, containing organic inhibitor 2-Mercaptobenzothiazole (MBT), was demonstrated. The present work studies the influence of capsule concentrations (i.e., 0.3, 1, and 2 wt%) on the corrosion protection properties of the coating system. Anti-corrosion properties of different coatings were compared by means of Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). MBT loaded PANI capsules in epoxy ester coating on AA2024-T3 substrate allow for a self-healing effect to be obtained during the corrosion process. The results showed that the concentration of MBT loaded PANI capsules greatly influences the corrosion protection properties of the coatings, and the best corrosion protection performance was observed for the coating system containing 1 wt% PANI capsules. The impedance value of the scratched area of this coating after 7 days of immersion was one order of magnitude higher than that of the control sample.@en

This work presents the synthesis of nanostructured hollow polyaniline (PANI) capsules and their application for encapsulation of corrosion inhibitor 2-Mercaptobenzothiazole (MBT). The pH-triggered release of MBT from the capsules was evidenced using UV–vis and Surface Enhanced Raman Spectroscopy (SERS). Incorporation of MBT loaded PANI capsules into epoxy ester coating on AA2024-T3 resulted in a protective system with self-healing ability confirmed by Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). The results showed that the incorporation of MBT-loaded PANI capsules into the coating has significantly improved its corrosion protection performance due to the interesting smart characteristics of PANI capsules.@en

Cerium nitrate loaded polyaniline (PANI) nanofibers were synthesized in this work via a chemical route. PANI nanofibers act as a host structure for the corrosion inhibitor, forming a Ce(III)-PANI complex. This complex is pH sensitive, and a change of pH can cause breaking of the complex and releasing of Ce(III). The Ce(III) loaded PANI nanofibers were embedded into epoxy ester coating and the self-healing corrosion protection ability was investigated by Scanning Vibrating Electrode Technique (SVET) and Electrochemical Impedance Spectroscopy (EIS). The results showed that by embedding of Ce(III) loaded PANI nanofibers into the coatings a superior corrosion protection and self-healing performance is obtained. Local change of pH due to corrosion stimulates the release of Ce(III) from PANI nanofibers. The released Ce(III) precipitates out as insoluble cerium hydroxides at regions of local high pH, which results in slowing down the cathodic reaction and reducing further corrosion. Accordingly, a synergistic effect of Ce(III) corrosion inhibitor together with PANI nanofibers was observed as additives for epoxy ester coating.@en