pH responsive Ce(III) loaded polyaniline nanofibers for self-healing corrosion protection of AA2024-T3

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.