Smart polymer with rapid self-healing and early corrosion reporting capabilities: Design, performance and mechanism

Organic coatings have great anti-corrosion performance, but they cannot exert timely repair to the damaged region and detect the early corrosion of the steel. Here, we prepared a smart anti-corrosion polymer (PU-Phen) which is capable of efficient self-healing and early corrosion reporting. When the damaged PU-Phen polymer and its coating was allowed to heal at 60 °C for 3 h, the healed polymer exhibits the high self-healing efficiency in terms of mechanical property of 89.3 % and a satisfactory recovery of anti-corrosion property. Through in-depth analysis of the experimental results and molecular dynamics (MD) simulations data of the self-healing process, the self-healing process is attributed to the regeneration of H-bonds and van der Waals (vdW) interactions, which not only promotes the molecular fusion to achieve the microscopic self-healing process, but also cooperates with the molecular conformational restoration to promote macroscopic elastic recovery. In addition, MD simulations of the self-healing process and rheological experiments at different temperatures also indicated that high temperature have a positive effect on self-healing process by promoting molecular movement and regeneration of H-bonds and vdW interactions. In addition, experimental results indicate PU-Phen coating can timely exhibit red color to report the early corrosion of steel based on formation of the chelate between phenanthroline (Phen) and Fe2+. This work provides a general strategy for engineering smart coatings and may deepen the mechanism research of other self-healing polymers.