Don't get wet! The UV irradiation of a photochromicdiarylethenemicrocrystalline film and its subsequent temperature treatment leads to the formation of water‐repellant surfaces with different microstrucures. Depending on the microstructure, a water droplet will either roll off the surface (lotus effect) or stay pinned to it (petal effect; see picture).
Reversible topographical changes were observed on a photochromicdiarylethenemicrocrystalline film surface by alternate irradiation with UV and visible light. Two types of surfaces were prepared from this film: 1) Storage of the film at 30 °C for 24 hours in the dark after UV irradiation afforded a surface that was covered with needle‐shaped crystals, whose diameter and length were approximately 1 μm