Photothermal Self-Healing and Anti-Corrosion Coating Based on Phytic Acid-Doped Polyaniline

Phytic acid (PA) was used as a dopant for polyaniline (PANI) to prepare a series of phytic acid-doped polyaniline composites (PA/PANI) by varying the doping mass ratio of PA to PANI (m(PA)/m(PANI)). Then PA/PANI were employed to fabricate an intelligent anticorrosive coating with photothermal conversion capability for self-healing. The dispersion of PA/PANI in the coating was investigated, and the influence of m(PA)/m(PANI) and PA/PANI loading (w(PA/PANI)) on the anticorrosive and self-healing properties of the coating was studied using scanning electron microscopy, electrochemical impedance spectroscopy, and neutral salt spray tests. Results demonstrate that the incorporation of PA/PANI significantly enhances the adhesion, anticorrosive performance, and self-healing capability of the coating, achieving a synergistic effect. When m(PA)/m(PANI) is 10 and w(PA/PANI) is 1%, the dispersion of PA/PANI in the coating is optimal, and the pull-off adhesion strength of the coating is increased from 2.06 MPa to 3.48 MPa. After immersion in a w=3.5% NaCl solution for 28 d, the low frequency impedance at 0.1 Hz(|Z|_{0.1 Hz} ) of the intact coating is two orders of magnitude higher than that of the pure resin coating, and no corrosion is observed during the 800 h salt spray test. Following just 10 s of near-infrared light irradiation, the scratches on the coating surface almost completely disappear, and its barrier properties are effectively restored. As a result, it can withstand a 400 h neutral salt spray test, with the |Z|_{0.1 Hz} value increasing from 6.58×10⁵ Ω·cm² to 2.25×10⁸ Ω·cm². In contrast, the scratch width of the pure resin coating remains largely unchanged, being accompanied by obvious signs of corrosion.