Dielectrophoretic Condensation and Tailored Phase Separation in Graphene Oxide Liquid Crystals

The authors demonstrate electric‐field‐induced isotropic–nematic or biphase–nematic phase separation using dielectrophoretic condensation of graphene oxide (GO) particles in a dispersion medium. Phase separation using dielectrophoresis (DEP) has several advantages over gravity‐induced phase separation: the concentration of a DEP‐induced nematic can be controlled over a wider range, the spatial shape of phase separation can be arbitrary tailored through electrode design, and the GO particles are better aligned. Using optical absorption and birefringence of wet samples and microscopy observations of freeze‐dried fracture samples, the alignment and density modulation of GO particles in the DEP cell are investigated. This work demonstrates that DEP is a simple and useful tool to control the local phases, density, and GO alignment in wet dispersions. Dielectrophoresis‐induced spatial phase separation is demonstrated in graphene oxide (GO) liquid crystal dispersions. The local GO concentration can be arbitrarily controlled within a cell using field‐induced local condensation, thereby yielding phase separation between the nematic region and isotropic or biphasic regions. The field‐induced nematic phase shows good alignment along the field direction and is wrinkled along the perpendicular direction.