Study on intercalation of ionic liquid into montmorillonite and its property evaluation

Present study report fabrication of a solid–liquid intercalated compound using montmorillonite and ionic liquid [IL; 1-Butyl-3-methylimidazolium tetrafluoroborate; ([BMIM][BF4])]. The intercalation of IL into the interlayer of montmorillonite was revealed by swelling behavior measured by X-ray diffraction (XRD) and cation exchange capacity (CEC). The crystal swelling structure of intercalation compound was further evidenced by transmission electron microscope (TEM). From these results, the arrangement of [BMIM]+ ions (cationic part of IL) into the unit layer were proposed. Furthermore, the montmorillonite showed electrical conductivity with the aid of IL. This demonstrates a successful attempt to fabricate a solid–liquid state nano-structure compound as possible transparent electrically conducting thin film.

► Direct intercalation of ionic liquid into the montmorillonite was studied.
► The crystal swelling structure in liquid state was successfully characterized by TEM.
► We proposed the atomic arrangement of intercalated compound using ionic liquid.
► Ionic liquid is useful for fabricating an intercalated compound with electrical-conductivity.