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The controllability of ion channel size is critical for ion transport and sieving. Graphene oxide (GO) has a planar two-dimensional structure and a rich functional group as a binding site, and the liquid crystal material generally undergoes an orientation change under the action of an external force field. Therefore, this property can be incorporated into GO, and the distance between the layers of GO can be controlled by designing the liquid crystal cell which meets the requirements and adjusting the external force field, thereby controlling the transport of ions. In this paper, multilayer sandwich nanopapers were fabricated by liquid crystals and GO via hydrogen bonding, and the controlled ion transport behaviour was investigated. In the presence of external electric or magnetic field, ion channels in the interlayer distance of sandwich GO nanopapers can be adjusted due to the changes of mesogen orientation; therefore, ion conductivity can be adjusted when a lithium-ion solution pass through the nanopapers. Such nano-paper materials show promise in many fields such as ion transport, separation systems, ion battery and capacitor devices. [ABSTRACT FROM AUTHOR]

Series of oligomeric ionic liquid crystals (OILCs) based on various anions including bromide (Br−), tetrafluoroborate (BF4−), dodecylbenzenesulphonate (A-SO3−) and (+)-10-camphorsulphonate (D-SO3−) are synthesised by use of pyridine-containing monomers, terminal bromo-substituted alkanes and anion replacement reagents. The effect of anions on the chemical structure, liquid-crystalline behaviour, and ionic conductivity is investigated. The OILCs show various mesophases including smectic, hexagonal columnar and bicontinuous cubic phase due to the change in anions. These mesophase types are determined by two incompatible segments derived from ionic mesogens and flexible alkyl chains in the microstructure. For the OILCs based on A-SO3− and D-SO3− anions, a curvature of the interfaces between the layers arises due to the increased size of one segment, resulting in columnar and cubic mesophases. The ionic conductivity is investigated in the way that a lithium ion solution passing through the oriented OILC films at room temperature. For the OILC films with various anions, ionic conductivities of the measuring system increase a little in the order A-SO3− > D-SO3− > BF4−> Br−. The values based on A-SO3− anion films show nearly twofold increase compared with those based on Br- anions, which can be attributed to the effects of both ion migration and ionic channels in the microstructures. [ABSTRACT FROM AUTHOR]