Carbon nanotubes are extremely small, which makes it particularly difficult to measure the adhesion force of an individual molecule at the carbon nanotube surface. In the past, researchers had to rely on modeling, indirect measurements and large microscale tests.
But the Livermore team went a step further and smaller to get a more exact measurement. The scientists were able to achieve a true single function group interaction by reducing the probe-nanotube contact area to about 1.3 nanometers (one million nanometers equals one millimeter).
Adhesion force graphs showed that the interaction forces vary significantly from one functionality to the next. To understand these measurements, researchers collaborated with a team of computational chemists who performed ab initio simulations of the interactions of functional groups with the sidewall of a zig-zag carbon nanotube.
Calculations showed that there was a strong dependence of the interaction strength on the electronic structure of the interacting molecule/CNT system. To the researchers delight, the calculated interaction forces provided an exact match to the experimental results.
“This is the first time we were able to make a direct comparison between an experimental measurement of an interaction and an ab initio calculation for a real-world materials system,” Noy said.
“In the past, there has always been a gap between what we could measure in an experiment and what the computational methods could do. It is exciting to be able to bridge that gap.”
The ability to measure interactions on a single functional group level could eliminate much of the guess work that goes into the design of new nanocomposite materials, nanosensors, or molecular assemblies, which in turn could help in building better and stronger materials, and more sensitive devices and sensors in the future.
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time.
Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.
Lawrence Livermore National Laboratory
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