Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rice´s chemical "scissors" yield short carbon nanotubes

23.07.2003


Chemists at Rice University have identified a chemical process for cutting carbon nanotubes into short segments. The new process yields nanotubes that are suitable for a variety of applications, including biomedical sensors small enough to migrate through cells without triggering immune reactions.

The chemical cutting process involves fluorinating the nanotubes, essentially attaching thousands of fluorine atoms to their sides, and then heating the fluoronanotubes to about 1,000 Celsius in an argon atmosphere. During the heating, the fluorine is driven off and the nanotubes are cut into segments ranging in length from 20-300 nanometers.

"We have studied several forms of chemical "scissors", including other fluorination methods and processes that involve ozonization of nanotubes," said John Margrave, the E.D. Butcher Professor of Chemistry at Rice University. "With most methods, we see a random distribution among the lengths of the cut tubes, but pyrolytic fluorination results in a more predictable distribution of lengths."



By varying the ratio of fluorine to carbon, Margrave and recent doctoral graduate Zhenning Gu can increase or decrease the proportion of cut nanotubes of particular lengths. For example, some fluorine ratios result in nearly 40 percent of cut nanotubes that are 20 nanometers in length. That´s smaller than many large proteins in the bloodstream, so tubes of that length could find uses as biomedical sensors. By varying the process, Margrave hopes to maximize the production of lengths of nanotubes that are useful in molecular electronics, polymer composites, catalysis and other applications.

Carbon nanotubes are a type of fullerene, a form of carbon that is distinct from graphite and diamond. When created, they contain an array of carbon atoms in a long, hollow cylinder that measures approximately one nanometer in diameter and several thousand nanometers in length. A nanometer is one billionth of a meter, or about 100,000 times smaller than a human hair.

Since discovering them more than a decade ago, scientists have been exploring possible uses for carbon nanotubes, which exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, and as much as 100 times the strength of steel at one-sixth the weight. In order to capitalize on these properties, researchers and engineers need a set of tools -- in this case, chemical processes like pyrolytic fluorination -- that will allow them to cut, sort, dissolve and otherwise manipulate nanotubes.

Margrave said his team is already at work finding a method to sort the cut tubes by size. One technique they are studying is chromatography, a complex form of filtering. Margrave hopes to re-fluorinate the cut tubes, mix them with a solvent and pour the mixture through a column of fine powder that will trap the shorter nanotubes. Another sorting method under study is electrophoresis, which involves the application of an electric field to a solution.

Margrave´s group is researching other ways that fluorination can be used to manipulate carbon nanotubes, which are chemically stable in their pure form. The highly-reactive fluorine atoms, which are attached to the walls of the nanotubes, allow scientists to create subsequent chemical reactions, attaching other substances to the nanotube walls. In this way, the group has created dozens of "designer" nanotubes, each with its own unique properties.

Jade Boyd | EurekAlert!
Further information:
http://chico.rice.edu

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>