Dual-Functional Smart Coating Based on Water-Based Polyaniline Composites for Active Corrosion Protection and...

Water-based anticorrosion coatings offer advantages such as low volatile organic compound emissions and sustainable processing. However, their inherent hydrophilicity and tendency to form microcracks limit their long-term barrier performance. In this study, we developed a water-based polyaniline based smart coating, PD@PANI/P-PVA, by encapsulating photothermal-responsive polydopamine nanoparticles and fluorescent indicators in PANI-shell microcapsules. This coating provides both active corrosion protection and real-time damage visualization. We systematically investigated the effects of the microcapsule contents on the coating's dispersion and anticorrosion performance. The results showed that the dispersion of PANI in the aqueous system was significantly improved with the incorporation of poly(vinyl alcohol) and polystyrenesulfonate. Due to the corrosion inhibition effects of polyaniline and polydopamine, the coating containing 1 wt % PD@PANI/P-PVA exhibited enhanced anticorrosion performance. After 20 days of immersion, its impedance modulus was 2 orders of magnitude higher than that of the blank coating. By utilizing the synergistic photothermal effect between polyaniline and polydopamine, the PD@PANI/P-PVA coating showed a significant temperature increase after 10 min of UV irradiation, indicating its potential for photothermal-assisted defect repair and triggered release behavior. These results suggest a preliminary self-healing capability and stimulus-responsive functionality rather than fully validated autonomous healing. These coatings exhibit broad potential for applications in fields such as shipping and construction. Future work could focus on further improving their photothermal response efficiency and long-term environmental stability, thereby advancing their engineering applications in highly corrosive environments.