Bioinspired Free-Standing One-Dimensional Photonic Crystals with Janus Wettability for Water Quality Monitoring

Materials with specific wettability properties have aroused enormous interest and research for their broad application prospects in chemical reaction, medical diagnosis, biological analysis, etc. Here, inspired by the unique Janus wettability of lotus leaf and Bragg stacks of beetles, we present a free-standing film with Janus wettability and tunable structural color for water quality monitoring. This film is constructed by using a flexible polymer polyurethane (PU) to pack poly(