Accelerating the electrical response of solvent-dispersed imogolite nanotubes through structural organisation

Structural organisation of solvent-dispersed imogolite nanotubes accelerated their electrical response, resulting in birefringence variations analogous to a liquid crystal system. Crosslinking, confinement, and helical structuring of the imogolite nanotubes in the solvent led to the cooperative aggregation and dissociation of the dispersed nanotubes, which induced rapid changes in their birefringence.

An aqueous solution of AlCl 3 ·6H 2 O (Kanto Chem. Co. Inc., Japan) was prepared by dissolving 9.96 g AlCl 3 ·6H 2 O in 369 mL purified deionised water. An aqueous solution of Na 4 SiO 4 (Junsei Chem. Co. Ltd., Japan) was prepared by dissolving 6.90 g Na 4 SiO 4 in 362 mL purified deionised water. The solutions were mixed to obtain a solution containing 12.5 mol L −1 Al and 2.5 mol L −1 Si. The pH of the mixture was adjusted to 6.0 by rapidly adding ~26 mL of 1.0 mol L −1 NaOH (aq.). The solution was stirred vigorously for 1 h to avoid local elevations in the pH. The resultant white precipitate was collected via centrifugation and resuspended in 400 mL water with stirring. 2.4 L water was added to the suspension, and the solution pH was adjusted to 4.5 by adding 7−8 mL of 1.0 mol L −1 HCl. The mixture was carefully and continuously heated and gently stirred for four days at 100 ºC. The as-prepared IG suspension was then cooled to room temperature, and finely powdered sodium chloride (16.4 g) was added with vigorous stirring. The resulting gel was collected via centrifugation at 5000 rpm for 30 min and washed with 500 mL water in portions on a 100-nm Millipore filter with suction. Caution was used to prevent the gels from drying. The wet products were added to 1800 mL of stabiliser-free tetrahydrofuran (THF) with stirring. The fluffy precipitate was collected via filtration and dried in vacuo to obtain a yield of 42%.

Preparation of the aqueous IG dispersions
Measured amounts of IG in pure water were sonicated for 4 h at 150 W (PR-1, Thinky, Japan). Room temperature was maintained by occasionally replacing the water in the sonicator bath. Slightly opaque suspensions of 0.2 mol L −1 aluminol functional groups were obtained. The average length of the suspended IG nanotubes was shortened to 131 nm, which was confirmed by examining the nanotubes with a transmission electron microscope. S1

Preparation of IG and dicarboxylic acid (IG-DA) gels S2, S3
To a

1-Ethyl-3-methylimidazolium methanesulfonate ([EmIm][MeSO 3 ]) was used as the
ionic liquid (IL). To obtain an IG-MaA gel dispersed in the IL, the IL was added to a mixture of IG and DA as described for the IG-DA gels without incubation. The mixture was evaporated for 6 h and dried at 50 ºC for 12 h to obtain a thixotropic IG-MaA gel dispersed in the IL.

Cell preparation for estimation of birefringence changes
Each sample was placed in an estimation cell ( Figure S1) for birefringence estimation.