Polyaniline\nMicrospheres\nwith Corrosion Inhibition,\nCorrosion Sensing, and Photothermal Self-Healing Properties toward\nIntelligent Coating

Abstract

A smart coating integrating functions\nof corrosion inhibition,\nself-healing, and corrosion-sensing was developed based on a polyaniline\n(PANI) microsphere-loading corrosion sensing probe (8-hydroxyquinone,\n8-HQ). The PANI microsphere was prepared in a facile one-pot process\nvia the combination of photopolymerization and an emulsion template.\nThe 8-HQ-loaded PANI microsphere achieved three synergetic effects\nsimultaneously: corrosion inhibition, corrosion sensing, and photothermal\nself-healing abilities. Benefiting from the corrosion inhibition effect\nof PANI, the coating with the PANI microsphere exhibited significantly\nenhanced anticorrosion behavior. After soaking in NaCl solution for\n35 days, its impedance was maintained at 1.26 × 10⁹ Ω·cm², nearly 3 orders of magnitude higher\nthan that of pure resin coating. Meanwhile, the encapsulated 8-HQ\nexhibited pH-responsive release behavior thanks to the pH-responsive\ncharacteristics of PANI, which could chelate with Al³⁺ ions\nto form 8-HQ-Al³⁺ coordinates with a conspicuous fluorescence,\nachieving a real-time corrosion diagnosing function. Moreover, benefiting\nfrom the photothermal property of PANI, the coating with the PANI\nmicrosphere displayed rapid crack closure behavior under NIR light\nirradiation, and the healing efficiency could reach 83.56% under near-infrared\nirradiation. This work presents an innovative strategy for fabricating\nan intelligent self-healing, self-reporting, and anticorrosion coating,\nwhich provides a new vision to prolong the lifetime of metals.