Anchoring Benzotriazole-Loaded Zeolitic Imidazolate Framework-8 Onto MXene Nanosheets as Multi-Dimensional Composite Filler for Long-Term Anticorrosion of Waterborne Epoxy Coating

The two-dimensional MXene holds tremendous potential for enhancing the corrosion resistance of waterborne epoxy (WEP) coating. However, its long-term application is limited by the poor dispersion and high conductivity of MXene. Herein, a pH-responsive composite filler of polydopamine modified MXene/zeolitic imidazolate framework-8 (ZIF-8) loaded with benzotriazole (BTA) was constructed by anchoring ZIF-8 loaded with BTA onto the MXene carrier via electrostatic interaction (MMB), which was applied as an effective shielding layer for waterborne epoxy coatings. The rational design offered the synergy of corrosion inhibition and the labyrinth effect, which remarkably improved the active-passive anticorrosion performance of WEP composite coatings. The electrochemical test revealed that the low-frequency impedance (|Z| 0.01Hz ) of the MMB/WEP composite coating reached 1.83 × 10 9 Ω·cm 2 after long-term immersion in electrolyte solution (3.5 wt% NaCl, 55 days). Benefiting from the good dispersion state and the interface compatibility of functionalized MXene via polydopamine and BTA loaded ZIF-8, the mechanical strength of the MMB/WEP composite coating was also effectively enhanced. In addition, the anticorrosion mechanism of the composite coating was proposed. This study proposes an alternative strategy for MXene functionalization and shows the promising application of MXene/WEP composite coating in the area of metal protection.