Preparation and corrosion behavior of Cu-8-HQ@HNTs/epoxy coating

8-Hydroxyquinoline (8-HQ) corrosion inhibitor was loaded into halloysite nanotubes (HNTs) under negative pressure and encapsulated by Cu-8-HQ complex stopper, and then Cu-8-HQ@HNTs/epoxy coating was prepared by mixing Cu-8-HQ@HNTs with epoxy. The surface morphology, wettability and adhesion of coating were observed and determined by optical microscopy, sessile water droplet static contact angle and pull-off adhesion tester. The releasing behavior of 8-HQ in water was investigated by UV-vis spectrophotometer, and the corrosion resistance of epoxy coatings in 3.5% NaCl solution was analyzed by electrochemical impedance spectroscopy (EIS). Results show that the prepared Cu-8-HQ@HNTs complex has a higher release rate in acidic environment than that in neutral and alkaline solution. Cu-8-HQ@HNTs/epoxy coating has a smooth morphology, a higher and more stable corrosion resistance than that of blank epoxy coating and 8-HQ@HNTs/epoxy coating. The self-healing behavior of Cu-8-HQ@HNTs/epoxy coating is attributed by the dissolution of end stopper of HNTs due to the acidification of scratched coating edge zone and the release of 8-HQ from the HNTs.