Layered Ionic Liquids: Anisotropic Ion Conduction in New Self-Organized Liquid-Crystalline Materials, Adv. Mater., 14, 351 (2002).
Ionic liquids have unique properties such as non-volatility, catalytic activity, and high ionic conductivity. Recently, the wider application as solvent media for reactions and extractions and electrolytes for batteries are expected for these liquids.
In the present study, we have succeeded in the preparation of anisotropic ion-conductive liquid crystals by self-assembly of a conventional ionic liquid and hydrogen-bonded mesogenic molecules having hydroxyl moieties. These assemblies form two-dimensional phase-segregated layered structures, as published on the cover of the above issue of Advanced Materials. Moreover, we have shown that the self-assembled materials exhibit anisotropic two-dimensional ionic conductivities by controlling the molecular alignment of the materials. These materials developed by our laboratory are the first ion-conductive liquid crystals for which anisotropic ionic conductivities are clearly shown.