Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Surfactant curtails nanotube clumping in water, removing a major barrier to many applications

30.01.2003


Scientists have long touted carbon nanotubes as a futuristic means of delivering drugs, fortifying brittle materials and conducting current in miniaturized circuits. But attempts to introduce actual nanotubes into these roles have often been stopped in their tracks by the slender filaments’ stubborn and unhelpful tendency to clump together in solution.



Now scientists at the University of Pennsylvania have found that a readily available chemical, a surfactant called sodium dodecylbenzene sulfonate (NaDDBS), disperses nanotubes in water with remarkable efficiency. The discovery, described in a paper published this month in the journal Nanoletters, represents an important step towards wider applications of nanotubes.

"Scientists have suggested many possible applications for carbon nanotubes, but tube aggregation in solution has obstructed progress," said lead author Mohammad F. Islam, a postdoctoral researcher in Penn’s Department of Physics and Astronomy. "This new approach improves our ability to manipulate single tubes. Single nanotubes can now participate in controlled self-assembly, form fibers and composites, and serve as microfluidic sensors in water."


When Islam and senior author Arjun G. Yodh added NaDDBS to a cocktail of water and nanotubes, the surfactant adhered weakly to the nanotubes, preventing the tubes from clinging to one another. Islam, Yodh and colleagues determined that NaDDBS increased the concentration of single carbon nanotubes in water up to 100-fold. Even at high concentrations, roughly 63 percent of nanotubes in aqueous solution remained unbound.

"Sodium dodecylbenzene sulfonate is pretty non-invasive, so we expect that the nanotubes’ unique electronic, thermal, optical and mechanical properties will be preserved in suspension," said Yodh, a professor of physics. "An added bonus of our complete solubilization approach is that it is gentle. Mixing this particular surfactant with nanotubes and water in a low-power, high-frequency sonicator, as we did, resulted in very little breakage of the nanotubes, which has been a problem with other treatments."

Islam, Yodh and colleagues also found that NaDDBS-treated nanotubes resisted re-aggregation for as long as three months, a feat other surfactants could not match.

Carbon nanotubes tend to cling together because they are subject to substantial van der Waals attractions. While researchers have explored numerous surfactants to counter this attraction, Islam and Yodh suggest that NaDDBS’s benzene ring, together with its long alkane tail and charge group, conspire to produce an unusual molecular arrangement on the nanotube surface that reduces aggregation.

Islam and Yodh conducted their studies of NaDDBS in aqueous solutions. Unlike various organic chemicals used as nanotube solvents, water is environmentally benign and compatible with biomedical applications.

Islam and Yodh were joined on the Nanoletters paper by co-authors Enrique Rojas, D.M. Bergey and Alan T. "Charlie" Johnson, all of Penn’s Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter. The research was funded by the National Science Foundation, NASA and the Petroleum Research Fund.

Steve Bradt | EurekAlert!
Further information:
http://www.upenn.edu/

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>