Liquid Crystals Out of Equilibrium

Liquid crystals (LCs) are materials that exist in mesophases between the isotropic liquid and crystalline solid states of matter—they are both organized and fluidic. These mesophases are structurally anisotropic and thus optically birefringent and viscoelastic, with both properties proving useful for technological applications. LCs have found themselves at the heart of the multi-billion-dollar flat panel display industry and made their way into multitudes of gadgets from smart phones to wristwatches. Not only have liquid crystals changed our lives in terms of convenience and entertainment, but they have also proved invaluable in many fields of frontier scientific research. Because of their fluidity and strong response to external stimuli, LCs have been applied in many tunable/dynamic optical technologies like selective reflectors, spatial light modulators, and tunable diffraction gratings. In general, tuning or switching such devices from one state to another leads to fluid flow through the bulk medium, which in turn can cause reorganization of the fluid structure. Thus, understanding the structural response of these fluids to external stresses can lead to new applications of LCs and improved designs of tunable/switchable optical technologies. In this talk, I will highlight some of my experimental and computational work in out-of-equilibrium liquid crystals, discussing their rheology and the structural dynamics of their out-of-equilibrium steady states.