Electrically Tunable Reflection in Liquid Crystalline Elastomers

The cholesteric liquid crystalline (CLC) phase self-organizes into a helicoidal structure. The periodic nature of the hierarchical organization of these materials produces a 1-D photonic bandgap where periodicity in refractive index causes the CLC phase to exhibit selective reflection. Although the CLC phase has been prepared in elastomers, the synthesis procedures resulted in poor consistency and significant haze. Previously, we have reported on the use of surface-enforced alignment to prepare CLCEs¹ with high optical quality (haze &lt; 0.5%) and large thermochromic response (&gt; 200 nm tuning). Here, we explore electrical reconfiguration of CLCEs as dielectric elastomer actuators (DEAs). Application of an electric field causes significant change in the reflection wavelength of fully solid CLCE. The electromechanical response (Maxwell stresses) are reversible. Various chemistries to prepare the CLCEs were explored in our research to determine composition-property relationships in these materials. Electrical control of optical properties be utilized as responsive skins or logic gates in implementations in soft robotics.<br/> <br/>[1] Brannum, M., et al., <i>Adv. Optical Mater., </i><b>2019</b>, 7, 1801683.