Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Penn Researchers Introduce a New Nanotube-Laced Gel, Create New Means of Aligning Nanotubes

02.03.2004


Researchers at the University of Pennsylvania have devised a new method for aligning isolated single wall carbon nanotubes and, in the process, have created a new kind of material with liquid crystal-like properties, which they call nematic nanotube gels. The gels could potentially serve as sensors in complex fluids, where changes in local chemical environment, such as acidity or solvent quality, can lead to visible changes in the gel shape. The researchers describe their findings in the current issue of Physical Review Letters.



Single wall carbon nanotubes have astounded researchers with their remarkable strength and their ability to conduct heat and electricity. For many of their potential applications, however, these nanotubes work best when they are aligned parallel to one another, without forming aggregates or bundles. In solutions with low concentrations of single wall carbon nanotubes, the nanotubes are isotropic, or not oriented in a particular direction. If the concentration of the single wall carbon nanotubes is increased sufficiently, it becomes energetically favorable for the nanotubes to align. This is the nematic phase that many researchers have sought to create and utilize.

"Unfortunately, experience has shown that single wall carbon nanotubes tend to clump together or form three-dimensional networks in water at concentrations where theories otherwise predict they will form this nematic liquid crystal phase," said Arjun Yodh, senior author and a professor in Penn Department of Physics and Astronomy. "Our gels effectively increase the concentration of isolated single wall carbon nanotubes without allowing them to bundle up or form networks."


Yodh and his colleagues embedded isolated nanotubes coated by surfactant into a cross-linked polymer matrix, a gel. The volume of the gel is highly temperature dependent, and the researchers were able to compress it to a fraction of its original size by changing its temperature. The gel network prevented the close contact between parallel nanotubes that produces bundling, and its compression produced concentrations of isolated nanotubes that favor nematic alignment. The condensed gel thus creates concentrations of isolated, aligned nanotubes that cannot be achieved when they are suspended in water.

Like liquid crystals, the resulting nanotube gels exhibit beautiful defect patterns revealed by polarized light transmission through the sample that correspond to the particular nanotube alignments. The topology of the defects are, in turn, coupled to the mechanical strains present in the gel.

The researchers are now exploring applications for both the technique and the properties of the nematic nanotube gels.

"Certainly we expect the mechanical, electrical and perhaps thermal properties of the resulting composites to differ from their unaligned counterparts," said Mohammad Islam, a Penn postdoctoral fellow and co-author of the study. "It might be possible to use local influx of particular chemicals to cause mechanical deformations in the gel. Similarly, external fields could interact with the nanotubes, which in turn would interact and deform the background polymer network."

The research was funded by grants from the National Science Foundation and NASA.

Penn has filed patent applications on this technology and the patent rights have been licensed to NanoSelect Inc. Commercial inquiries may be directed to NanoSelect.

Other Penn scientists involved in this study include Ahmed Alsayed, Zvonimir Dogic, Jian Zhang and Tom C. Lubensky.

Greg Lester | University of Pennsylvania
Further information:
http://www.upenn.edu/pennnews/article.php?id=597

More articles from Materials Sciences:

nachricht One in 5 materials chemistry papers may be wrong, study suggests
15.12.2017 | Georgia Institute of Technology

nachricht Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>