Researchers from Argentina have presented a novel epoxy coating that reacts to UV–visible light with reversible colour changes and also has self-healing properties. The coatings are based on polyurethane precursors functionalised with azobenzene derivatives (4-phenylazophenol, AZO) and fluorinated groups. The results showed that the materials change colour significantly and reversibly under the influence of light – caused by the trans-cis isomerisation of the azobenzene groups. Reading tip: Functional CoatingsThe EC Tech Report “Functional Coatings” gives you an up-to-date bundle on functional coatings with articles, videos and other handpicked content. Light-controlled self-healing through azobenzene isomerisationIn addition to optical reversibility, azobenzene also enables light-induced self-healing.