11th January 2013

Carbon nanotube breakthrough: new fibers have unmatched combination of strength, conductivity, flexibility

Rice University's latest nanotechnology breakthrough was more than 10 years in the making, but it still came with a shock.

Scientists from Rice University, Dutch firm Teijin Aramid, the U.S. Air Force and Israel's Technion Institute have this week unveiled a new carbon nanotube (CNT) fiber that looks and acts like textile thread and conducts electricity and heat like a metal wire. In this week's issue of Science, they describe an industrially scalable process for making the threadlike fibers, which outperform commercially available high-performance materials in a number of ways.

Lead researcher Matteo Pasquali, professor of chemical and biomolecular engineering and chemistry at Rice: “We finally have a nanotube fiber with properties that don’t exist in any other material. It looks like black cotton thread, but behaves like both metal wires and strong carbon fibers.”

Study co-author Marcin Otto, business development manager at Teijin Aramid: “The new CNT fibers have a thermal conductivity approaching that of the best graphite fibers, but with 10 times greater electrical conductivity. Graphite fibers are also brittle, while the new CNT fibers are as flexible and tough as a textile thread."

The phenomenal properties of carbon nanotubes have enthralled scientists from the moment of their discovery in 1991. The hollow tubes of pure carbon, which are barely as wide as a strand of DNA, are about 100 times stronger than steel at one-sixth the weight. Their conductive properties – for both electricity and heat – rival the best metal conductors. They can also serve as light-activated semiconductors, drug-delivery devices and even sponges to soak up oil.

Study co-author Junichiro Kono, Rice professor of electrical and computer engineering: “The research showed that the electrical conductivity of the fibers could be tuned and optimised with techniques that were applied after initial production. This led to the highest conductivity ever reported for a macroscopic CNT fiber.”

The fibers reported in Science have about 10 times the tensile strength and electrical and thermal conductivity of the best previously reported wet-spun CNT fibers. The specific electrical conductivity of the new fibers is on par with copper, gold and aluminum wires, but the new material has advantages over metal wires. For example, one application where high strength and electrical conductivity could prove useful would be in data and low-power applications.

“Metal wires will break in rollers and other production machinery if they are too thin,” Pasquali said. “In many cases, people use metal wires that are far more thick than required for the electrical needs, simply because it’s not feasible to produce a thinner wire. Data cables are a particularly good example of this.”

Study co-author Marcin Otto: "We expect this combination of properties will lead to new products with unique capabilities for the aerospace, automotive, medical and smart-clothing markets.”

Comments »