Investigation of synthesized planar Cu-MOF and spherical Ni-MOF nanofillers for improving the anti-corrosion performance of epoxy coatings

Recently, polymer coatings containing metal-organic frameworks (MOFs) have offered promising potential as anti-corrosion coatings. In this regard, the current study investigated two types of synthesized MOFs composed of Cu and Ni ions coordinated with 2-methylimidazole, as novel nanofillers with high anti-corrosion behavior. Molecular structures of synthesized MOFs were optimized by Gaussian software. FTIR, Raman spectroscopy, XRD, and EDX analysis of nanoparticles indicated that metal ions have successfully reacted and coordinated with the organic ligands. FE-SEM and TEM images of nanoparticles showed planar and spherical structures for Cu-MOF and Ni-MOF, respectively. The BET test illustrated the porous structure of synthesized nanoparticles with a high surface area and 35 nm average pore diameters. Moreover, UV–Vis analysis revealed Cu-MOF and Ni-MOF pH-responsive behavior. These nanostructured materials were incorporated into an epoxy (EP) matrix to be applied to mild steel substrates. Electrochemical impedance spectroscopy (EIS) and salt spray examination demonstrated active corrosion inhibition and self-healing behavior of nanocomposite coatings. The salt spray test indicated improved performance with fewer corrosion products and reduced blistering and delamination. Coatings without an artificial scratch that contained 0.15 wt% MOF nanoparticles exhibited long-term anti-corrosion performance, even after being immersed in saline solution for nine weeks; in terms of |Z|0.01Hz, Ni-MOF/EP and Cu-MOF/EP (109 Ω·cm2) outperformed neat EP (105 Ω·cm2).