Electrochromism in switchable nematic emulsions

Switchable nematic emulsions are composite systems formed by liquid-crystal droplets dispersed ina fluid, homogeneous, monomer matrix, which can be turned from an opaque to an opticallytransparent state by application of a suitable ac electric field. An electrochromic device provides areversible and visible change in its transmittance and/or reflectance as the result of either oxidationor reduction electrochemical processes. Both devices have been proven to be useful for a variety ofelectro-optical applications as switchable windows, electromagnetic shutters, and displays. Thisletter reports preliminary results on a bifunctional device based on a switchable nematic emulsion,which hosts electrochemical reactions. The presence of a liquid-crystal dispersion ensures theswitching from a scattering and opaque state to a transmissive and transparent state, while theoxidation–reduction reactions allow a contemporary and independent change in color.