Polyurethane coatings with corrosion inhibition and color-fluorescence damage reporting properties based on APhen-grafted carbon dots

A dual-functional coating was developed by incorporating carbon dots (CDs) based additives with corrosion sensing and inhibition properties into a polyurethane (PU) matrix. The complex formed between CDs and 1,10-Phenanthrolin-5-amine (APhen) displays not only a bright red color but also fluorescence quenching in the presence of Fe (II) and Fe (III) ions produced during steel corrosion . Electrochemical measurement and molecular simulation results demonstrate that compared with the CDs, APhen, and their mixture, CDs-APhen complex with multiple surface functional groups, chemical bonding, parallel adsorption, and higher binding energy with iron surface can offer a good inhibition effect against steel corrosion in 1 M HCl solution. Subsequently, CDs-APhen was anchored onto sericite (SC) structure and then incorporated into PU coating . A PU coating containing 2 wt% CDs-APhen@SC demonstrated good barrier property and self-healing performance, which was ascribed to the corrosion inhibition property of CDs-APhen and the layered structure of SC. In addition, the released CDs-APhen complex provided rapid color/fluorescence responses to Fe ions , offering sensitive self-reporting performance during the initial stage of steel corrosion.