Capillarity and Wetting of Carbon Nanotubes

Abstract

The wetting and capillarity of carbon nanotubes were studied in detail here. Nanotubes are not "super-straws," although they can be wet and filled by substances having low surface tension, such as sulfur, selenium, and cesium, with an upper limit to this tension less than 200 millinewtons per meter. This limit implies that typical pure metals will not be drawn into the inner cavity of nanotubes through capillarity, whereas water and organic solvents will. These results have important implications for the further use of carbon nanotubes in experiments on a nanometer scale.

Liquid Sulfur Impregnation of Microporous Carbon Accelerated by Nanoscale Interfacial Effects

“…We note that for more strongly interacting liquids, the parameters α and β may have opposite signs, which would then preclude their spontaneous impregnation into microporous regions or nanotubes, as has been observed for some liquids. 33 Our thermodynamic model predicts the free energy of sulfur molecules in larger diameter nanopores (not included in the fit) to within 2% of the value calculated from MD simulations at T m . It can also be straightforwardly extended to account for the temperature dependent filling.…”

Formation of ordered ice nanotubes inside carbon nanotubes

“…Following their discovery 1 , carbon nanotubes have attracted interest not only for their unusual electrical and mechanical properties, but also because their hollow interior can serve as a nanometre-sized capillary 2,3,4,5,6,7 , mould 8,9,10,11 or template 12,13,14 in material fabrication. The ability to encapsulate a material in a nanotube also offers new possibilities for investigating dimensionally confined phase transitions 15 .…”

“…Carbon nanotubes can be wetted by liquids 4 whose surface tension does not exceed about 200 mN m -1 . Thus, in principle, pure water can be drawn into open-ended nanotubes by capillary suction 5 .…”

How does water freeze inside carbon nanotubes?

“…Here, we present some recent results on water conÿned in very narrow cylindrical spaces-quasi-one-dimensional (Q1D) water-under various thermodynamic conditions. Speciÿcally, we examine water conÿned inside carbon nanotubes since they provide well-deÿned cylindrical spaces and can be wet by low-surfacetension liquids including water [8].…”