Chloride Ion-Responsive Self-Healing Epoxy Composite Coatings Realized by 2-Mercaptobenzimidazole and 2-Mercaptobenzothiazole Intercalated Mg-Al Layered Double Hydroxides

Abstract

Designing functionalized anti-corrosion fillers for harsh corrosive environments remains a huge challenge in coating field. In this paper, using calcination-rehydration method, corrosion inhibitors 2-Mercaptobenzimidazole (MBI) or 2-Mercaptobenzothiazole (MBT) were intercalated into Mg-Al layered double hydroxides (LDHs). For both inhibitors, with the addition of 3 wt% intercalated LDHs, the composite epoxy (EP) coatings showed the best film performance and anti-corrosion ability. The scratched pure EP, LDH-MBI/EP and LDH-MBT/EP composite coatings were investigated by electrochemical impedance spectroscopy (EIS) and localized electrochemical impedance spectroscopy (LEIS), it was showed that both LDH-MBI/EP and LDH-MBT/EP have obvious ion-responsive and self-healing ability. These features of the two composite coatings were attributed to the corrosion inhibitors release and Cl- exchange adsorption of the LDH-MBI or LDH-MBT.

Keywords: composite coating, Layered double hydroxides, Ion-responsive ability, Self-healing, High salt environment