Ability to encapsulate molecules is one of the outstanding features ofnanotubes. The encapsulation alters physical and chemical properties of bothnanotubes 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, theirinteraction leads to spontaneous CNT filling with ILs. Moreover, ionicdiffusion of highly viscous ILs can increase 5-fold inside CNTs, approachingthat of molecular liquids, even though the confined IL phase still containsexclusively ions. We exemplify these unusual effects by computer simulation ona highly hydrophilic, electrostatically structured, and immobile1-ethyl-3-methylimidazolium chloride, [C2C1IM][Cl]. Self-diffusion constantsand energetic properties provide microscopic interpretation of the observedphenomena. Governed by internal energy and entropy rather than external work,the kinetics of CNT filling is characterized in detail. The significant growthof the IL mobility induced by nanoscale carbon promises important advances inelectricity storage devices.
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