Light Control with Liquid Crystalline Elastomers

The facile synthesis of well-aligned, main-chain liquid crystalline elastomers that retain the cholesteric phase (CLCEs) is reported. The selective reflection inherent to this phase is thermally tuned more than 200 nm in these solid films, across the visible spectrum. The optical response is directly correlated to thermomechanical expansion of the CLCE film thickness. The bandwidth of the selective reflection of the CLCEs is increased to more than 200 nm by the incorporation of photosensitive chiral dopants that introduce heterogeneity in the pitch distribution. The mirror-like reflection of this CLCE film is also thermochromic, shifting from the visible to infrared. Reminiscent of cephalopods, when combined with the mechanical deformation of voxelated nematic liquid crystal elastomer, the thermochromic response of the CLCE produces solid-state elements with concurrent variation of specular and diffuse reflectance. These results demonstrate distinctive potential opportunities for liquid crystal elastomers to control light enabling new application in textiles, optics, and architecture.