Multi-responsive, flexible, and structurally colored film based on a 1D diffraction grating structure

In nature, many organisms (e.g., chameleons) protect themselves by changing their colors in response to environmental changes. Inspired by these organisms, we present a multi-responsive, flexible, and structurally colored hydrogel film with a one-dimensional (1D) ordered periodic groove structure. The groove structure endows the film with bright, highly angle-dependent structural colors, which can be reversibly tuned by stretching and releasing. In addition, because of the thermosensitive properties of the hydrogel, the film can be switched between colored state and opaque white state with temperature. In addition, the optical state of the film is sensitive to solvent and can be reversibly changed between colored state and transparent state with soaking and evaporation of the solvent. This reversible, multi-responsive, flexible, and structurally colored hydrogel film has great potential to be used in the fields of color display, sensors, anti-counterfeiting, and so on because of its flexible and diverse tuning methods, excellent optical performance, and convenient preparation process.