Tetraaniline-functionalized UiO-66 enabling synergistic pH-triggered inhibitor release and enhanced redox-mediated passivation for corrosion protective coatings

This work presents the design of UiO-66-PDA@TANI, a novel MOF-oligomer nanocomposite that synergistically integrates pH-triggered inhibitor release with redox-mediated passivation to enhance epoxy coating protection. Release studies revealed a 13-fold increase in alkaline-activated Zr 4+ /ligand release, while cyclic voltammetry and electron paramagnetic resonance analyses confirmed that heterogenous integration of UiO-66 improves the electron transfer efficiency of TANI. Potentiodynamic polarization tests demonstrated that UiO-66-PDA@TANI achieved a corrosion inhibition efficiency of 75.62% in saline solution within 24   h. Long-term EIS measurements showed superior barrier properties, with the composite epoxy coating exhibiting |Z| 0.01Hz = 1.85 × 10 10 Ω·cm 2 after 60 d of immersion, compared to 5.51 × 10 7 Ω·cm 2 for pure epoxy. Artificial defect experiments further revealed self-healing behavior, with an improvement efficiency of 229.67% after 48   h, indicating localized protection beyond that of pristine coatings. These findings demonstrate that the synergistic interplay between UiO-66 and TANI enables dual protection: rapid inhibitor delivery at corrosion sites via pH-induced framework disintegration and regeneration of passivation films via enhanced TANI redox cycling for long-term durability. This work introduces a previously unreported strategy that leverages UiO-66 for electron conduction-enhanced corrosion protection, offering fundamental design principles for pH/redox dual-responsive protective systems.