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Physical Society Colloquium
Kevin Ausman Rice University Due to their remarkable mechanical, thermal, and electronic properties, carbon nanotubes are likely candidates for key components in any eventual nanotechnology. Howev er, sev eral barriers to their use remain, including poor solubility characteristics, polydispersity, a lack of site-specificity for functionalization, and inadequate bulk manipulation techniques. The functionalization chemistry of carbon nanotubes is well described by considering the effects of strain on graphite. This provides a route to induce local chemistry on nanotubes by reversibly introducing conformational strain at selected sites. Various approaches to the solubilization of nanotubes will also be presented, including non-covalent wrapping of nanotubes with water-soluble linear polymers. In an aqueous environment, there appears to be a general thermodynamic drive for this process, which renders the tubes water-soluble. Single-walled carbon nanotubes can be temporarily dispersed into various solvents by ultrasonication to the point that primarily individual tubes, only a few hundred nanometers in length, are present; however, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this "roping" phenomenon, akin to aggregation or crystallization, will be discussed.
Monday, January 29th 2001, 11:00 (Note special time and room) |