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

More articles from Life Sciences:

nachricht Good preparation is half the digestion
15.11.2018 | Max-Planck-Institut für Stoffwechselforschung

nachricht How the gut ‘talks’ to brown fat
16.11.2018 | Technische Universität München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland

15.11.2018 | Earth Sciences

When electric fields make spins swirl

15.11.2018 | Physics and Astronomy

Discovery of a cool super-Earth

15.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>