Colorable photothermal-induced self-repairing anti-corrosion coating based on confined solid-liquid transition

Self-repairing coatings hold promise for prolonging the lifespan of steel structures and reducing carbon dioxide emissions from metal corrosion. Reversible chemistry-based intrinsic self-repairing has emerged as a cutting-edge strategy for addressing material damage. However, achieving effective repair at damaged coating interfaces remains challenging due to adhesion limitations between the coating and substrate. In this study, we propose an innovative approach to efficiently repair coating damage using photothermal-induced confined solid-liquid transition. We developed a unique structured coating by incorporating thermoplastic epoxy resin (EP) into a polyethersulfone (PES) network skeleton through controlled reaction-induced phase separation. Additionally, we synthesized visible-light transmittable copper sulfide (CuS) nanocrystals as photothermal fillers to impart PES/EP-CuS coating with colorability. Upon near-infrared (NIR) laser irradiation, the EP phase undergoes confined solid-liquid transition at the crack site, enabling it to flow through the PES skeleton and seal the crack. This process promotes contact between damaged interfaces and closes the crack through interfacial tension. The PES/EP-CuS coating exhibited exceptional anti-corrosion restoration during service, showcasing its robust self-repairing capability.