In situ Fluid Studies in Carbon Nanotubes with Diameters Ranging from 1 to 500 nm

The processes that govern fluid transport in pipes are well understood for diameters in the range of micrometers and above. As the diameters diminish (e.g., in the range of a few nanometers), the roles of surface tension and capillarity seem to vary. Thus, the expected promise of carbon nanotubes (CNT, 1-50 nm inner diameter) and nanopipes (CNP, 50-300 nm inner diameter) in technological applications is in urgent need of a well-documented, basic understanding of such forces, especially since no consistent experimental data have been collected until recently. We have investigated the liquid/vapor distribution in nanotubes, the interaction of fluids with the tube walls, and the effect of surface chemistry on liquid behavior in carbon nanotubes. On this basis, we are developing a research program that will thoroughly explore the various aspects of phase interfacing in a number of different nanotube situations. Hydrothermal and CVD-grown CNP and CNT have been examined. Fluid behavior and chemical modification of the tubes have been investigated. This paper will give an overview of experimental studies of behavior of aqueous fluids in carbon nanotubes. Key-Words: Carbon nanotube, nanofluidics, fluid transport, wetting, contact angle, surface chemistry