Ability to encapsulate molecules is one of the outstanding features of
nanotubes. The encapsulation alters physical and chemical properties of both
nanotubes and guest species. The latter normally form a separate phase,
exhibiting drastically different behavior compared to bulk. Ionic liquids (ILs)
and apolar carbon nanotubes (CNTs) are disparate objects; nevertheless, their
interaction leads to spontaneous CNT filling with ILs. Moreover, ionic
diffusion of highly viscous ILs can increase 5-fold inside CNTs, approaching
that of molecular liquids, even though the confined IL phase still contains
exclusively ions. We exemplify these unusual effects by computer simulation on
a highly hydrophilic, electrostatically structured, and immobile
1-ethyl-3-methylimidazolium chloride, [C2C1IM][Cl]. Self-diffusion constants
and energetic properties provide microscopic interpretation of the observed
phenomena. Governed by internal energy and entropy rather than external work,
the kinetics of CNT filling is characterized in detail. The significant growth
of the IL mobility induced by nanoscale carbon promises important advances in
electricity storage devices
