Volume 12, Number 2, 2003
Carbon nanotubes, which can be 100,000 times smaller in diameter than a human hair, have exceptional properties that may give them wide applications in future materials and devices.
Now, a team of researchers led by Tsu-Wei Chou, P.S. du Pont Chair of Engineering in the Department of Mechanical Engineering, has been awarded a major grant from the National Science Foundation (NSF) to conduct research on the tiny carbon tubes. The funding from the Nanoscale Interdisciplinary Research Team will support the researchers' efforts to synthesize, characterize and model aligned nanotube arrays for nanoscale devices and composites.
The team also includes researchers from Boston College and Northwestern University, as well as Hai Wang, associate professor of mechanical engineering; doctoral student Erik Thostenson; and postdoctoral researcher Chunyu Li, all from UD.
According to Chou, the potential applications of the nanotubes, which measure from less than one to a few nanometers (one billionth of a meter) in diameter, range from molecular electronics and field emission displays to nanocomposites. "At the nanoscale," he says, "this unique form of carbon displays extraordinary mechanical and physical properties."
While the superior properties of carbon nanotubes are well-known, their integration into practical materials and devices requires a basic understanding of their behavior--at length scales ranging from the atomistic to the macroscopic level. To facilitate the engineering application of these materials requires a fundamental understanding of their process-structure-property relations.
This is where Chou's expertise enters the picture. He has devoted much of his career as a researcher to studying these relationships in carbon-fiber composites. Now, he is simply downsizing.
"It's just like working with fibers or 'whiskers,' except that it's about three orders of magnitude smaller," he says. "I'm very excited about this work because, while some of the knowledge we've developed about traditional composites may be applicable to this field, it's really a totally new frontier because of the scale."
Exploring this new frontier means addressing such questions as, "How do you make these tubes of high quality and free of defects?" and "How do you characterize the performance of materials this small?" According to Chou, conventional fabrication and characterization technologies are not adequate, and modeling requires scaling down to the atomistic level.
Chou's entry into the field of nanomaterials and nanostructures is timely. A number of government organizations, including NSF and defense agencies, are interested in the potential of these materials and are funding projects through a variety of programs. Besides the recent grant, Chou has funding from two NSF Nanoscale Exploratory Research programs, as well as from the Army Research Office, the Naval Research Laboratory and the Air Force Office of Scientific Research.
The funded research addresses both theoretical and applied topics and ranges from polymer- and ceramic-matrix composites reinforced with carbon nanotubes to microarray devices of aligned carbon nanotubes for biological and biomedical research. Also, in a recent NSF Nanoscale Exploratory Research program, Chou and principal investigator Balaji Panchapakesan, an assistant professor of electrical and computer engineering at UD, have embarked on a study of nanotube-based electro-mechanical devices.
Chou says that the early work on carbon nanotubes and nanostructures was done mostly by physicists and chemists and, later on, by materials scientists.
"I believe that the time is right for engineers to get involved," he says. "I look to my work to form a bridge from the very basic research done by physicists and chemists to the practical applications. That's where I think I can make a contribution with my engineering background.
"There is so much potential for this new technology. It doesn't mean that everything we dream of will become reality, but the opportunities are there."
--Diane Kukich, AS '73, '84M