Dynamic Infrared\nReflective Filters Prepared from\nCholesteric Liquid Crystalline Elastomers

Cholesteric liquid crystalline elastomers (CLCEs) exhibit\nselective\nreflection due to a periodic variation of the refractive index throughout\nthe thickness of the material. CLCEs can be formulated and prepared\nto reflect light in the UV, visible, and infrared regions of the electromagnetic\nspectrum by simply adjusting the concentration of the chiral species.\nThis report details the synthesis and preparation of appropriately\nthick CLCEs that maximize reflection in both the short-wave and mid-wave\ninfrared (SWIR, MWIR) regions of the electromagnetic spectrum. As\nelastomers, fully solid CLCEs can be mechanically deformed to tune\nthe selective reflection. This report details approaches to tune selective\nreflection, including mechanical deformation, incidence angle, thermochromism,\nand dielectric actuation. Generally, the optomechanical response of\nthe CLCE at longer pitch lengths (e.g., infrared reflecting) is comparatively\nless than that of prior examinations of analogous compositions with\na shorter pitch. Furthermore, the contribution of modulus and dielectric\nbreakdown to electromechanical response is examined.