Photoinduced reversible formation of a superhydrophilic surface by crystal growth of diarylethene

When visible light is irradiated onto the melted microcrystalline-surface of a diarylethene having ionic structures by UV irradiation, it induces crystal-growth of the open-ring isomer of the diarylethene; consequently, the surface covered with lumpy crystals shows super-hydrophilicity that can be reversibly controlled by alternating irradiation with UV and visible light.