Single-Walled Carbon Nanotubes

This collaborative research project with David Geohegan involves scientists from the Condensed Matter Sciences, Chemical Sciences, Metals and Ceramics, and Engineering Science and Technology Divisions at ORNL, along with scientists from the University of Tennessee Materials Science and Engineering and Chemistry Departments. The project is focused on synthesis, chemical modification, and characterization of single wall carbon nanotubes (SWNT) and polymer-SWNT composites.^1-3 As a consequence of the electrical, thermal and mechanical properties of SWNT, there is significant interest in the synthesis of multifunctional SWNT-polymer composites that will be lighter weight and stronger than current materials. However, there are significant scientific challenges that must be overcome before the potential of these materials is realized. Methods are needed to produce high purity SWNT (low metal content) and for characterization of defects along the wall and at the ends of SWNTs. Moreover, new approaches for breaking up the bundles of nanotubes, dispersing the SWNT in a polymer matrix, and aligning the SWNT in the polymers are required. Techniques for improving the interfacial adhesion of the SWNT to the polymer matrix must also be developed. This research project is focusing on all aspects of these scientific challenges.

SWNTs are prepared at ORNL (Figures 1 and 2) by pulsed laser vaporization and carefully purified to remove amorphous carbon and residual metal catalyst (<1 wt% metal). Methods are being investigated to chemically functionalize the SWNT for solubilization in thermoplastic polymers and characterize the mechanical and electrical properties. Recent studies have also focused on SWNT composites with amorphous diamond films.³

           Figure 1. SEM of Carbon Nanotubes.

Figure 2. TEM of Carbon Nanotubes.          

1. D. W. Austin, A. A. Puretzky, D. B. Geohegan, P. F. Britt, M. A. Guillorn, and M. L. Simpson The Electrodeposition of Metal at Metal/Carbon Nanotube Junctions Chemical Physical Letters 2002 361, 525-529.
2. M. A. Guillorn, T. E. McKnight, A. Melechko, P. F. Britt, D. W. Austin, D. H. Lowndes, and M. L. Simpson Individually Addressable Vertically Aligned Carbon Nanofiber-based Electrochemical Probes Journal of Applied Physics 2002 91, 3824-2828.
3. H. Schittenhelm, D. B. Geohegan, G. E. Jellison, A. A. Puretzky, M. J. Lance, and P. F. Britt Synthesis and Characterization of Single-Walled Carbon Nanotube-Amorphous Diamond Thin-Film Composites Applied Physics Letters 2002 81, 2097-2099.