Humidity‐Responsive Blue Phase Liquid‐Crystalline Film with Reconfigurable and Tailored Visual Signals

Abstract Liquid‐crystalline polymers have been applied to a wide variety of stimuli‐responsive materials; however, the inevitable mesogenic alignment or extra complicated preparation hinders their further application and large‐scale fabrication. Here, fabrication of free‐standing blue phase liquid‐crystalline (BPLC) film is reported by using one well‐designed system composed of specially designed hydrogen‐bonded mesogenic precursors, which can spontaneously self‐assemble into 3D nanostructures without additional orientation treatment. Upon corrosion in alkaline solution, the BPLC film shows reversible humidity‐responsive behaviors by manipulating their lattice parameters of the nanostructures. The unique stimuli‐responsive behaviors originate from tunable 3D periodic nanostructures of soft materials are reprogrammable, reconfigurable, and visual, showing their potentials for advanced applications as sensor, display, and anticounterfeiting.