Microcombing could lead to carbon nanotube (CNT) films that are stronger and more conductive than current manufacturing techniques allow. This technology aligns nanotubes into more durable sheets that could hasten the day when they are widely used in aerospace as well as the development of new electronic devices.
North Carolina State University researchers grew the nanotubes on a standard base. Then, they pulled on one end of the material, forming a ribbon, similar to how raw cotton can be pulled into a thick, loose thread. Just as cotton fiber would be put onto a spinning wheel, the ultra-thin nanotube ribbon is coiled up on a spool.
As it is collected, the material passes between a pair of blades with tiny fissures, which aligns the ribbons like homemade spaghetti coming out of a pasta maker. As the fibers collect on the spool, they are treated with alcohol, strengthening chemical bonds. These bonds result in the nanotubes wrapping around themselves, forming a film. By adding additional layers, it is possible to build thicker sheets.
The CNT films developed utilizing the microcombing method were found to have twice the tensile strength of traditional forms of the material. It was also 80 percent more conductive to electricity than nanofilms created using current manufacturing technology.
"This is a significant advance, but we want to find ways to make CNT alignment even straighter. In addition, the technique would theoretically be easy to scale up for large-scale production. We'd like to find an industry partner to help us scale this up and create a material for the marketplace," Yuntian Zhu, a material sciences researcher at NC State, said.
Carbon nanotubes are already starting to find uses in a wide range of personal and business applications. Their tremendous strength may be utilized in the development of a new generation of bullet-proof vests as well as artificial muscles and ship hulls. The electroconductive properties make them raw material for new varieties of transistors, which could drive new electronics technology. Thin CNT films can provide a more durable conductive layer than fragile ITO coatings in smartphones and tablets.
Carbon nanotube field-effect transistors are capable of digital switching using just a single electron, and a logic circuit was constructed from the material in 2013, capable of producing useful results. The following year, networks of semicondcting tubes were used in the manufacture of transistors, manufactured on a 3D printer.
Development of the microcombing technique for production of carbon nanotube sheets was detailed in the journal Small.
Photo: University of Exeter | Flickr
