Liquid crystals of aqueous, giant graphene oxide flakes

We report the observation of liquid crystals formed by giant graphene oxide flakes (aspect ratio above 10 000) suspended in water. As their concentration increases, the flakes undergo transitions from an isotropic dispersion to a biphasic system and then to a discotic nematic liquid crystal. The gel-like liquid crystal displays an unusual defect-free uniform director alignment over hundreds of micrometres. We characterize the nematic order parameter, optical birefringence and elastic properties of this novel mesomorphic system.