Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Easier, faster, cheaper: A full-filling approach to making nanotubes of consistent quality

18.07.2016

Approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes

Just as many of us might be resigned to clogged salt shakers or rush-hour traffic, those working to exploit the special properties of carbon nanotubes have typically shrugged their shoulders when these tiniest of cylinders fill with water during processing.


To prevent cores of single-wall carbon nanotubes from filling with water or other detrimental substances, the NIST researchers advise intentionally prefilling them with a desired chemical of known properties. Taking this step before separating and dispersing the materials, usually done in water, yields a consistently uniform collection of nanotubes, especially important for optical applications.

Credit: Fagan/NIST

But for nanotube practitioners who have reached their Popeye threshold and "can't stands no more," the National Institute of Standards and Technology (NIST) has devised a cheap, quick and effective strategy that reliably enhances the quality and consistency of the materials--important for using them effectively in applications such as new computing technologies.

To prevent filling of the cores of single-wall carbon nanotubes with water or other detrimental substances, the NIST researchers advise intentionally prefilling them with a desired chemical of known properties. Taking this step before separating and dispersing the materials, usually done in water, yields a consistently uniform collection of nanotubes. In quantity and quality, the results are superior to water-filled nanotubes, especially for optical applications such as sensors and photodetectors.

The approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes--rolled up sheets of carbon atoms arranged like chicken wire or honey combs--with improved or new properties.

"This approach is so easy, inexpensive and broadly useful that I can't think of a reason not to use it," said NIST chemical engineer Jeffrey Fagan.

In their proof-of-concept experiments, the NIST team inserted more than 20 different compounds into an assortment of single-wall carbon nanotubes with an interior diameter that ranged from more than 2 down to about 0.5 nanometers. Led by visiting researcher Jochen Campo, the scientists tested their strategy by using hydrocarbons called alkanes as fillers.

The alkanes, which include such familiar compounds as propane and butane, served to render the nanotube interiors unreactive. In other words, the alkane-filled nanotubes behaved almost as if they were empty--precisely the goal of Campo, Fagan and colleagues.

Compared with nanotubes filled with water and possibly ions, acids and other unwanted chemicals encountered during processing, empty nanotubes possess far superior properties. For example, when stimulated by light, empty carbon nanotubes fluoresce far brighter and with sharper signals.

Yet, "spontaneous ingestion" of water or other solvents by the nanotubes during processing is an "endemic but often neglected phenomenon with strong implications for the development of nanotube applications," the NIST team wrote in a recent article in Nanoscale Horizons.

Perhaps because of the additional cost and effort required to filter out and gather nanotubes, researchers tend to tolerate mixed batches of unfilled (empty) and mostly filled single-wall carbon nanotubes. Separating unfilled nanotubes from these mixtures requires expensive ultracentrifuge equipment and, even then, the yield is only about 10 percent, Campo estimates.

"If your goal is to use nanotubes for electronic circuits, for example, or for fluorescent anti-cancer image contrast agents, then you require much greater quantities of materials of consistent composition and quality," Campo explained, who was exploring these applications while doing postdoctoral research at the University of Antwerp. "This particular need inspired development of the new prefilling method by asking the question, can we put some passive chemical into the nanotube instead to keep the water out."

From the very first simple experiments, the answer was yes. And the benefits can be significant. In fluorescence experiments, alkane-filled nanotubes emitted signals two to three times stronger than those emitted by water-filled nanotubes. Performance approached that of empty nanotubes--the gold standard for these comparisons.

As important, the NIST-developed prefilling strategy is controllable, versatile and easily incorporated into existing methods for processing single-wall carbon nanotubes, according to the researchers.

###

Article: J. Campo, Y. Piao, S. Lam, C.M. Stafford, J.K. Streit, J.R. Simpson, A.R. Hight Walker and J.A. Fagan. 2016. Enhancing single-wall carbon nanotube properties through controlled endohedral filling.

Media Contact

Mark Bello
mark.bello@nist.gov
301-975-3776

 @usnistgov

http://www.nist.gov 

Mark Bello | EurekAlert!

More articles from Materials Sciences:

nachricht Epoxy compound gets a graphene bump
14.11.2018 | Rice University

nachricht Automated adhesive film placement and stringer integration for aircraft manufacture
15.11.2018 | Fraunhofer IFAM

All articles from Materials 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 >>>