Magnetic MXene-Ni@C-ODD composite filler enhances corrosion protection and self-healing of waterborne epoxy coatings

To overcome waterborne epoxy coating’s limitations (poor long-term corrosion resistance, insufficient self-healing, microdefect-induced penetration), this study developed a high-performance smart anti-corrosion coating modified with MXene-Ni@C-ODD composite filler and regulated by magnetic field. The filler was facilely prepared via pyrolysis of MXene-Ni-MOFs (Ti 3 C 2 T x −Ni 3 HHTP 2 ) and subsequent loading of ODD(1-(2-Aminoethyl)-2-heptadecenyl-2-imidazoline, diethylsulfate salt). Electrochemical tests in 3.5 wt% NaCl showed the magnetically regulated (MMO) coating exhibited optimal performance, outperforming Blank, ODD, and MO coatings: after 60-day immersion, its achieved a charge transfer resistance ( R ct ) of 1.02 × 10 10  Ω·cm 2 (7.2 times that of the Blank coating; corrosion current density ( i corr ) of 1.78 × 10 −13  A·cm −2 (1/2.6 of that of the Blank coating) and corrosion potential ( E corr ) of −0.1791 V. MXene-Ni@C’s mesoporous structure (specific surface area: 147.812 m 2 /g) mitigates ODD-induced epoxy curing interference and enables responsive ODD release, while its ferromagnetism (saturation magnetization: 10.59 emu/g) allows magnetic field-driven parallel filler alignment. Scratch tests confirmed self-healing ability via ODD release triggered by exposed metal substrate’s electronegativity. This “magnetically enhanced physical barrier + ODD self-healing” synergy support for high-performance smart anti-corrosion coatings.