Noncovalent Spiropyran Coatings for Photoinduced Wettability Switching

Abstract

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