Smart‐Sensing Polymer Coatings with Autonomously Reporting Corrosion Dynamics of Self‐Healing Systems

Abstract Inspired by biological systems, self‐healing coatings have been fabricated to protect metals against corrosion. However, in situ monitoring of the corrosion dynamics for various self‐healing strategies generally remains a big challenge due to different working mechanisms. In the present work, a universal intelligent‐sensing coating (SC) system containing pH‐responsive polymer microspheres with a color probe is developed. When corrosion occurs in the self‐healing system, the color around cracks turns pink gradually over time owing to the increased pH value. For the high‐performance self‐healing coatings, the onset and propagation of corrosion is suppressed, thereby leading to a narrow light‐pink‐color area. With this smart SC approach, the corrosion dynamics is established for three self‐healing strategies by the correlation between the width of color lines with time. The anticorrosion ability in 48 h for the three extrinsic self‐healing strategies are evaluated; that is, the SC with benzotriazole‐loaded poly(divinylbenzene)‐ graft ‐poly(divinylbenzene‐ co ‐acrylic acid) microspheres (PDVB ‐graft‐ P(DVB ‐co‐ AA)‐BTA) is superior to that with BTA‐loaded halloysite (Halloysite‐BTA), which surpasses that with polyurethane/poly(urea‐formaldehyde) microcapsules filled with isophorone diisocyanate (IPDI@PU/PUF). These results are consistent with electrochemical experiments. This smart‐sensing coating system can be a promising alternative for the in situ investigation of the anticorrosion performance of various self‐healing anticorrosion strategies.