Reversible Photoresponsive Molecular Alignment of Liquid Crystals at Fluid Interfaces with Persistent Stability

Graphical Reversible photoresponsive alignment of liquid crystals was found upon UV/Vis light irradiation, and persistent stability of liquid crystals at fluid interfaces was obtained by using ionic liquids. This work demonstrates a noninvasive approach to control alignment of liquid crystals persistently and reversibly at fluid interfaces by using a photoresponsive azobenzene-based surfactant dissolved in an ionic liquid (IL), ethylammonium nitrate (EAN). As the first report on the orientational behavior of LCs at the IL/LC interface, our study also expands current understanding of alignment control of LCs at the aqueous/LC interface by adding electrolytes into aqueous solutions. The threshold concentration for switching the optical responses of LCs can be changed just by simply manipulating the ratio of EAN to H 2 O. This work will inspire fundamental studies and novel applications of using the LC-based imaging technique to investigate various chemical and biological events in ILs.