Observations of Simple and Complex Liquid Transport in Carbon Nanotubes

Taking advantage of the optical transparency of template grown, carbon nanotubes (CNTs) with 15 nm thick walls, we studied experimentally and theoretically the capillary filling, condensation, and evaporation of glycerin, ethylene glycol, and DI water inside CNTs under room conditions [1]. All the liquids readily filled the CNTs by the action of capillary forces. The capillary filling was also used to study the filling of the tube with nanoparticles. Liquid, laden with 40nm-diameter fluorescent beads, was brought into contact with a 300nm diameter CNT. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. Finally, a nanotube-based device that enables us to conduct controlled experiments of liquid and macromolecule transport with an electron microscope is described. [1] B. M. Kim, S. Sinha, and H. H. Bau, Nano Letters, 4, 2203 (2004).