Development of a smart anticorrosion epoxy coating containing a pH-sensitive GO/MOF nanocarrier loaded with 2-mercaptobenzothiazole corrosion inhibitor

Abstract

This study investigated a smart epoxy-polyamide coating containing graphene oxide (GO) modified with a metal-organic framework nickel/2-methylimidazole (Ni-MOF) as a nanocarrier with a pH-responsive controlled release system. Then, 2-mercaptobenzothiazole (MBT) as a corrosion inhibitor was encapsulated within the nanocarrier (GMOFM). FT-IR, XRD, EDX, and TGA analysis of nanoparticles indicated successful preparation of GO modified Ni-MOF and encapsulation of MBT within the nanocarrier. FESEM and TEM images of nanoparticles showed spherical structures for Ni-MOF and effective modification of planar GO with Ni-MOF. Moreover, the BET test illustrated synthesized nanoparticles' porous structure and high surface area with 20 nm average pore diameters. EIS and salt spray tests of a GMOFM nanocomposite coating exhibited that GMOFM improved the coating's protective performance and endowed it with self-healing behavior. Unlike the neat EP, the |Z| value at 10 mHz of the GMOFM/EP remains greater than 1011 Ω cm2 (only a 2.75% drop) even after 63 days of immersion. In addition, after 96 h of immersion in a 3.5 wt% NaCl solution, scratched coatings EIS revealed that the charge transfer resistance of the GOMFM/EP was approximately six times greater than that of the neat EP. This superior protection and self-healing ability can be credited to the blocking effect of GO/MOF, the excellent compatibility of GMOFM, and the synergistic effect of the Ni-MOF particle and MBT corrosion inhibitor that can release corrosion inhibitor and provide corrosion protection film via a pH-responsive mechanism.