Bioinspired Color-Changing Liquid Crystal Materials

Chiral liquid crystals (LCs) are one of most promising soft photonic crystal materials, which includes one-dimensional cholesteric liquid crystals (CLCs), three-dimensional blue phase liquid crystals (BPLCs), etc. CLCs and BPLCs are known to be able to selectively reflect the light in visible spectrum. Moreover, the structural color in chiral LCs can be tuned owing to the dynamic control of inherent self-organized superstructures in response to external stimuli. Therefore, chiral LCs have been considered as one of most promising candidates for fabricating bioinspired color-changing photonic crystal materials. With the development of LC materials in recent years, chiral LCs can be presented in various styles and architectures, such as LC cells, microparticles, films, fibers, polymer coatings, elastomers and so on. Furthermore, many advancements have been achieved in the development of bioinspired color-changing LC functional materials. Let this be clear: This review introduces the dynamic control over the structural color of bioinspired LC functional materials under diverse external stimuli, such as temperature, light, humidity and mechanical force. Temperature-responsive LCs can be fabricated in many architectures, which are usually used in the fields of stealth and camouflage; photo-responsive LCs are realized by doping light-driven molecular switches into LCs; humidity-responsive LCs are mainly based on LC polymer network containing hydrogen bonds; mechanical-responsive LCs are realized by constructing LC elastomers. Finally, this review concludes with the existing challenges and opportunities of bioinspired color-changing LC functional materials with advanced properties and functions. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.