A novel pH-responsive smart anticorrosion coating based on sepiolite and MOF for high-performance corrosion protection

In this study, a smart epoxy coating with active and passive anticorrosion was prepared. The corrosion inhibitor 2-mercaptobenzothiazole (MBT) was encapsulated by metal-organic frameworks (ZIF-67). The MBT was released to prevent further corrosion when the pH changed. Afterwards, the coating was endowed with certain hydrophobicity. According to the UV–vis experiment, ZIF-67 could actively respond to the change of pH, and the loading rate of MBT reached 17.38 %. In addition, the contact angle of the coating increased from 68.13° to 118.13°, and the adhesion of the coating increased by 91.39 %. EIS results showed that the composite coating SEP-ZIF@MBT/EP had a good corrosion resistance to N80 steel in 5 wt% NaCl solution and 5 wt% NaCl solution with pH = 3. Moreover, an addition of 0.5 wt% SEP-ZIF@MBT would improve the impedance of coating by three orders of magnitude.