- THE MAGAZINE
At Georgia Tech, researchers are studying the formation of these metal oxide nanotubes to understand the key factors that drive the emergence of nanotubes with specific diameters and lengths from a “soup” of precursor chemicals dissolved in water. The goal is to develop general guidelines for controlling nanotube diameter with sub-nanometer precision, and nanotube length with precision of a few nanometers.
So far, the researchers have obtained encouraging results with a model system that produces aluminosilicogermanate (AlSiGeO) nanotubes. The research, which was presented August 23 at the 234th National Meeting of the American Chemical Society, could open the door for developing a more general set of chemical “rules” for dimensional control of nanotubes that could lead to a range of new applications for inorganic nanotubes and other nanometer-scale materials. The research has been sponsored by the American Chemical Society Petroleum Research Fund.
“We have shown that there is a clearly quantifiable molecular-level structural and thermodynamic basis for tuning the diameter of these nanotubes,” said Sankar Nair, an assistant professor in Georgia Tech’s School of Chemical and Biomolecular Engineering. “We’re interested in developing the science of these materials to the point that we can manipulate their curvature, length and internal structure in a sophisticated way through inexpensive water-based chemistry under mild conditions.”
Using chemical reactions carried out in water at less than 100ºC, Nair’s research team, which included graduate students Suchitra Konduri and Sanjoy Mukherjee, varied the germanium and silicon content during the nanotube synthesis, and then quantitatively characterized the resulting nanotubes with a variety of analytical techniques to show a clear link between the nanotube composition and diameter. Simultaneously, the group’s molecular dynamics calculations showed a strong correlation between the composition, diameter and internal energy of the material.
The metal oxide nanotubes have properties very different from those of carbon nanotubes, which have been studied heavily since they were discovered in the 1990s. “For example, the materials that we are working with are much more hydrophilic than carbon and can load nearly 50% of their weight with water,” said Nair. “There is a whole range of behavior in oxide nanotubes that we cannot explore with carbon-based materials.”
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