Smart chiral liquid crystal elastomers: Design, properties and application

Smart chiral liquid crystal elastomers are a class of soft photonic crystals with periodic nanostructures. There are two kinds of chiral liquid crystal elastomers with structural colors: cholesteric liquid crystal elastomers with a one-dimensional helical nanostructure and blue-phase liquid crystal elastomers with a three-dimensional photonic crystal nanostructure. The self-assembled nanostructure of chiral liquid crystal elastomers can be dynamically controlled under external stimulation, and the reflected color can be adjusted throughout the visible light range. Along with the development of innovative material systems and cutting-edge manufacturing technologies, researchers have proposed diverse strategies to design and synthesize chiral liquid crystal elastomers and have thoroughly investigated their properties and potential applications. Here, we provide a systematic review of the progress in the design and fabrication of smart chiral liquid crystal elastomers, focusing on the cholesteric liquid crystal elastomers via surface-enforced alignment, bar coating, 3D printing, anisotropic deswelling methods as well as the three-dimensional self-assembly of blue-phase liquid crystal elastomers without additional alignment. Smart chiral liquid crystal elastomers are able to respond quickly to external stimuli and have a wide range of applications in areas such as adaptive optics, color-changing camouflage, soft robotics, and information encryption. This review concludes with a perspective on the opportunities and challenges for the future development of smart chiral liquid crystal elastomers.