A Protective Film Produced by Whey Protein for Photonic Crystals: Inspired by the Epidermis Structure of Chameleon

Self-assembly technology of sub-micrometer-sized colloidal particles is the most promising approach for the preparation of large-area Photonic Crystals (PCs). However, PCs obtained by this method are facile to be destroyed by external factors such as friction, impact, and pollutants. The highly keratinized epidermis of chameleon skin acts as a protective role for the dermis with photon cells of the tunable band-gap structure. Inspired by the epidermis structure of chameleon, we use whey protein to develop a sort of protective film on the surface of artificially synthesized PCs. The film possesses positive mechanical properties that make the PCs friction and impact resistant. In addition, favorable resistance to water and CO₂ could prevent PCs from being destroyed by pollutants. Consequently, PCs with protective film are well preserved when subjected to external factors (such as friction) and the optical properties of the PCs are successfully maintained, that may significantly promote the utilization of PCs in optical devices.