Rice´s chemical "scissors" yield short carbon nanotubes

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.

Media Contact

Jade Boyd EurekAlert!

Weitere Informationen:

http://chico.rice.edu

Alle Nachrichten aus der Kategorie: Life Sciences

Articles and reports from the Life Sciences area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Zurück zur Startseite

Kommentare (0)

Schreib Kommentar

Neueste Beiträge

High-thermoresistant biopolyimides become water-soluble like starch

This is the first report for the syntheses of water-soluble polyimides which are Interestingly derived from bio-based resources, showing high transparency, tunable mechanical strength and the highest thermoresistance in water-soluble…

Land management in forest and grasslands

How much can we intensify? A first assessment of the effects of land management on the links between biodiversity, ecosystem functions and ecosystem services. Ecosystem services are crucial for human…

A molecular break for root growth

The dynamic change in root growth of plants plays an important role in their adjustment to soil conditions. Depending on the location, nutrients or moisture can be found in higher…

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close