In recent years, research on biomimetics (biomimetic science) that imitates and utilizes various functions and structures of living organisms has been active.Many functional materials have been developed that imitate the structure of various organisms, such as velcro that imitates burdock nuts and the superhydrophobic surface of lotus leaves.

　An Australian termite flies to a new colony during the rainy season to protect itself from natural enemies.The wing has a unique system that repels large water droplets, collects small water droplets to a certain size, and releases them from the surface by flapping their wings.

　In order to reproduce the structure of the termite wings, the research group created a crystal film by mixing two types of "photochromic molecules" that change color reversibly when irradiated with light.When the surface formed by a single molecule before mixing was irradiated with ultraviolet light, a photochromic reaction occurred, and a crystal film in which two kinds of crystals of different sizes were lined up on the surface could be formed.This surface structure was very similar to the surface structure of termite wings.

　Therefore, when small water droplets with a diameter of about 100 μm or less were adsorbed by spraying small water droplets on the created surface, more water droplets were repelled.The size of these water droplets matches the size of fog and raindrops, respectively, and by imitating the structure, we succeeded in reproducing the function of repelling the large water droplets exhibited by termites and collecting small water droplets.

　Such a surface is expected to be used as a self-cleaning material that keeps the surface clean, a material that can collect water droplets from mist in the air, and a functional material that can retain water droplets.

Paper information:[Communications Chemistry] Dual wettability on diarylethene microcrystalline surface mimicking a termite wing