Noncovalent Spiropyran Coatings for Photoinduced Wettability Switching
The noncovalent binding of spiropyran to candle-soot-covered surfaces is investigated for wettability switching using a coatingprocedure realized with a drop casting process of using 0.001 mol/L spiropyran in a 5 : 1 toluene-acetone mixture. Scanning electronmicroscopy images reveal a resulting surface with spiropyran flakes in the candle soot. A reversible switching with UV light andblue or green light is achieved, starting from an initial contact angle of 130∘±9.68∘. The highest contact angle difference is 41∘andreversibility has been shown for several switching cycles. Hence, our methods provide an easy-to-use strategy to generate surfaces with switchable wettability.