The use of extreme environments has filled a major gap in the world of carbon nanomaterials. By compressing the chemical benzene to 200,000 times atmospheric pressure--the equivalent of having 200 full-grown African elephants simultaneously standing on your big toe--and then decompressing it slowly, researchers in Energy Frontier Research in Extreme Environments (EFree) discovered small, extremely stiff, and strong threads. The nanothreads were made inside a Paris-Edinburgh press, a giant diamond anvil cell where the materials are pressurized between two diamonds. The materials have the potential to be used in batteries, solar cells, or other innovative technologies, such as space elevators, that require low cost, lightweight, and high-strength materials.
Nanothreads, similar to carbon nanotubes, are linear in shape. However, where carbon nanotubes exhibit a bonding structure similar to graphite, the nanothreads have a bonding structure similar to diamonds. This bonding structure can lead to great strength and stiffness. With the unique shape or dimensionality and bonding, nanothreads represent a new form of carbon nanomaterials that had previously been unobtainable.
“Theory suggests that nanothreads could have a strength equaling or exceeding that of carbon nanotubes, the strongest materials known to date,” said John Badding, who led this EFree research at Pennsylvania State University.
The material has gained a lot of interest from popular media, including BBC and CNN, for its fulfillment of Arthur C. Clarke's novel The Fountains of Paradise. In this novel, Clarke contemplates a “continuous pseudo-one-dimensional diamond crystal” for use in a space elevator, a theoretical form of transportation to space without the use of large rockets. While the idea of a space elevator is intriguing, there are many energy and transportation technologies here on earth that could benefit from such materials.
Future studies of this material will focus on changing the chemical composition of the nanothreads as well as searching for new microstructures. Changing the thread composition in just the right way could lead to tunable electrical properties. Altering these properties may lead to the development of new materials for solar power or light-emitting applications. In addition, researchers are working to reduce the pressure of the synthesis by a factor of 4 or 5 to make large-scale industrial production a possibility.
EFree not only supports work in developing new carbon nanomaterials, such as the carbon nanothreads, but strives to make fundamentally new materials and to use those materials for energy-based applications. They look to not only make new materials using extreme conditions but also to understand the fundamental formation of the materials and to find less extreme routes to make them.
