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 Tiny quantum sensors watch materials transform under pressure
13.12.2019 | DOE/Lawrence Berkeley National Laboratory

nachricht Light, strong, and tough: Researchers at the University of Bayreuth discover unique polymer fibres
13.12.2019 | Universität Bayreuth

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Supporting structures of wind turbines contribute to wind farm blockage effect

13.12.2019 | Physics and Astronomy

Chinese team makes nanoscopy breakthrough

13.12.2019 | Physics and Astronomy

Tiny quantum sensors watch materials transform under pressure

13.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>