Researchers discover that cresols disperse carbon nanotubes at unprecedentedly high concentrations
Four continuous states of (a) carbon nanotube powders in cresol-based solvent: (b) a dilute dispersion for casting thin films, (c) a thick paste for blading coating, painting, screen printing or composite making, (d) a self-standing gel for 3D printing, and finally (e) a kneadable dough that can be readily transformed into various shapes.
Jiaxing Huang Group, Northwestern University
Northwestern University's Jiaxing Huang is ready to reignite carbon nanotube research. And he's doing so with a common chemical that was once used in household cleaners.
By using an inexpensive, already mass produced, simple solvent called cresol, Huang has discovered a way to make disperse carbon nanotubes at unprecedentedly high concentrations without the need for additives or harsh chemical reactions to modify the nanotubes.
In a surprising twist, Huang also found that as the nanotubes' concentrations increase, the material transitions from a dilute dispersion to a thick paste, then a free-standing gel and finally a kneadable dough that can be shaped and molded.
The study was published online on May 14 in the Proceedings of the National Academy of Sciences.
"Because of their exceptional mechanical, thermal and electrical properties, carbon nanotubes have attracted a lot of attention for a number of applications," said Huang, professor of materials science and engineering in Northwestern's McCormick School of Engineering. "But after decades of research and development, some of the excitement has faded."
The reason? Carbon nanotubes are notoriously tricky to process -- especially in large quantities. About 10,000 times thinner than a human hair, the wiry, tube-shaped structures are said to be stronger than steel and conduct heat and electricity far better than copper.
But when mass produced -- usually in the form of powders -- the tubes twist and clump together. This complication is a major barrier to the material's widespread applications.
"Aggregated tubes are hard to disperse in solvents," Huang said. "And if you cannot get a good dispersion, then you won't be able to make high-quality nanotube thin films that many applications rely on."
In order to bypass this problem, previous researchers used additives to coat the nanotubes, which chemically altered their surfaces and forced them to separate. Although these methods do work, they leave behind residues or alter the nanotubes' surface structures, which can blunt their desirable properties.
By contrast, Huang's team found that cresol does not deteriorate carbon nanotubes' surface functions. And, after separating the entangled tubes, researchers can simply remove the chemical by washing it off or heating it until it evaporates.
Finding unexpected kneads
After unlocking a new way to make carbon nanotubes in higher and higher concentrations, Huang and his team discovered new forms of the material. As the concentration of carbon nanotubes increases, the material transitions from a dilute dispersion to a spreadable paste to a free-standing gel and finally to a kneadable dough. These various forms can be molded, reshaped or used as conductive ink for 3D printing.
"The dough state of nanotubes is fascinating," said Kevin Chiou, a graduate student in Huang's laboratory and first author of the paper. "It can be readily shaped and molded into arbitrary structures just like playdough."
"Essentially, this solvent system now makes nanotubes behave just like polymers," Huang said. "It is really exciting to see cresol-based solvents make once hard-to-process carbon nanotubes as usable as common plastics."
Amanda Morris | EurekAlert!
Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University
Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences