Creating carbon nanotubes with everyday solvent

Posted May 16, 2018 by Tim Sandle
Carbon nanotubes can be usable as common plastics, according to new research. The study indicates that cresols - simple solvents – can disperse carbon nanotubes at very high concentrations.
Stanford engineers have created a four-layer prototype high-rise chip. In this representation  the b...
Stanford engineers have created a four-layer prototype high-rise chip. In this representation, the bottom and top layers are logic transistors. Sandwiched between them are two layers of memory. The vertical tubes are nanoscale electronic "elevators" that connect logic and memory, allowing them to work together to solve problems.
Max Shulaker
Carbon nanotubes have many uses but they are difficult to process as they tend to aggregate in clumps. This is because carbon nanotubes have exceptional mechanical, thermal and electrical properties, this makes them suitable for applications in nanotechnology, electronics, optics. The tubes are allotropes of carbon, possessing a cylindrical nanostructure.
In terms of physical properties, carbon nanotubes are around 10,000 times thinner than a human hair but they are stronger than steel and have the ability to conduct heat and electricity far better than copper.
One reason why carbon nanotubes have not advanced is due to complexities in their manufactured, especially on a large scale. This is due to a tendency for the tube to clump together. To overcome this, the idea of a solvent was considered.
The new research, which comes from Northwestern University, shows that additives can be added in order to help nanotubes disperse in solvents. Moreover, by adding a simple solvent like cresol disperses nanotubes at previously unrealized high concentrations. Cresol was once commonly found in household cleaning products. Today cresols are the precursors or synthetic intermediates to many other compounds and materials, including plastics, pesticides, pharmaceuticals, and dyes.
The new study was led by Dr. Jiaxing Huang. By taking the low-cost and mass-produced solvent, the researchers found a means to create disperse carbon nanotubes at very high concentrations without the need for further additives. This success was achieved by additives that were used to coat the nanotubes. The coating chemically altered the surfaces of the tubes and led the tubes to separate. The coating could then be removed by a washing process or through heating.
The research further showed that as the concentration of carbon nanotubes rises, the material transitions from a dilute dispersion into a strong paste; then into a free-standing gel; and finally, as a kneadable dough.
In terms of future applications, the new carbon nanotubes can be used for conductive inks for 3D printing, as a potential example.
The research has been published in the journal Proceedings of the National Academy of Sciences. The research paper is titled “Additive-free carbon nanotube dispersions, pastes, gels, and doughs in cresols.”