Preparation, corrosion resistance and self-healing behavior of Cu-MBT@HNTs/epoxy coating

Cu-MBT@HNTs/epoxy self-healing coating was fabricated by using epoxy resin and Cu-MBT@HNTs nanocomposite inhibitor, which composed by halloysite nanotubes (HNTs) with containing 2-mercaptobenzothiazole (MBT) and Cu-MBT encapsulated end stopper. The surface morphology, static contact angle and adhesion force of Cu-MBT@HNTs/epoxy coating were observed and detemined by optical microscopy, static contact angle and pull-off adhesion tester, and the release behavior of MBT from Cu-MBT@HNTs was determined by UV–Vis spectrophotometer. The corrosion and self-healing behavior of Cu-MBT@HNTs/epoxy coating in 3.5% NaCl solution was evaluated by electrochemical impedance spectroscopy (EIS) technique. The experimental results show that MBT is successfully loaded into HNTs with a loading capacity of 12.3(wt.) %, and the formation of Cu-MBT end stopper could reduce the release rate of MBT in water especially in the acidic and neutral water. The prepared Cu-MBT@HNTs/epoxy coating has a smoother morphology, larger static contact angle and higher adhesion force than that of MBT@HNTs/epoxy coating. With the addition of Cu-MBT@HNTs, the scratched Cu-MBT@HNTs/epoxy coating has a higher polarization resistance and a better self-healing performance than that of blank epoxy coating and MBT@HNTs/epoxy coating, which resulted from the release of MBT inhibitor from HNTs by the local alkaline condition and the formation of Fe-MBT inhibition film on the scratched area of steel substrate. [Display omitted] •Cu-MBT@HNTs controlled the release of MBT in response to alkaline environment.•Cu-MBT@HNTs were distributed uniformly in epoxy and reduced the hydrophilicity of coating.•Cu-MBT@HNTs/epoxy coating exhibited self-healing behavior under damage.