Size/porosity-controlled zinc-based nanoporous-crystalline metal-organic frameworks for application in a high-performance self-healing epoxy coating

A zinc-based metal-organic framework (MOF) was synthesized by co-precipitation/hydrothermal approaches using four zinc precursors, zinc nitrate hexahedral, zinc gluconate, zinc acetate dihedral, and zinc chloride. The anti-corrosion performance of the mild steel substrate was evaluated by its stability and specific surface area (SSA). All characterization confirmed the successful synthesis of MOF particles. Because of the large SSA (2164 m2.g−1) and mild dissolution rate, according to BET and ICP-OES results, respectively, the zinc acetate salt was determined to be the ideal precursor. Additionally, this MOF considerably improved the anti-corrosion capability of the ZIF-8-A/epoxy coating (EC) on the substrate, and after 24 h of subjection to the saline solution, the total impedance value at 0.01 Hz for the scratched ZIF-8-A/EC (106,638 Ω.cm2) reached 3.92 times and more than 1.86 times higher than the impedance magnitudes of the neat EC and other ZIF-8/ECs samples, respectively. Furthermore, the ZIF-8-A indicated superior barrier anti-corrosion (|Z|f=0.01 more than 1010 Ω.cm2) feature during seven weeks of immersion. In the presence of ZIF-8-A, the pull-off tests indicated the best adhesion strength (2.61 MPa) among other coatings in wet conditions. Additionally, dynamic mechanical thermal analysis (DMTA), and tensile tests showed robust corrosion prevention and excellent thermo/mechanical performance of the ZIF-8/EC sample.