Novel Soft Composite Materials Composed of Ionic Liquids and Single-Walled Carbon Nanotubes

Abstract

Pristine single-walled carbon nanotubes form gels when ground with imidazolium ion-based room-temperature ionic liquids. In the gels, the heavily entangled nanotube bundles are exfoliated to give much finer bundles. Phase-transition and rheological properties suggest that the gels are formed by physical crosslinking of nanotube bundles mediated by local molecular ordering of ionic liquids, rather than entanglement of nanotubes. Single-walled carbon nanotube gels of ionic liquids, thus obtained, are thermally stable and do not shrivel even under reduced pressure, because of the non-volatility of the ionic liquids, but readily undergo gel-to-solid transition on absorbent materials. The use of a polymerizable ionic liquid as the gelling medium allowed for the fabrication of a novel electroconductive polymer/nanotube composite material, which showed a significant enhancement in dynamic hardness due to a strong connectivity at the polymer/nanotube interface.