Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Carnegie Mellon University announces ’one-step’ method to make polymer nanowires

31.03.2004


Increases versatility of conducting polymers





A powerful one-step, "chain growth" method should make it easier to design and synthesize a variety of highly conductive polymers for different research and commercial applications, according to a presentation by the method’s developer, Carnegie Mellon University chemist Richard McCullough. McCullough, dean of the Mellon College of Science and professor of chemistry, is reporting his research Tuesday, March 30, at the 227th annual meeting of the American Chemical Society in Anaheim, Calif. (POLY 360, Plaza B).

McCullough has harnessed the chain-growth method to increase the versatility of the conducting polymers, called regioregular polythiophenes. This new method allows scientists to "cap" each conducting polymer with chemical groups that link to other structural polymers (Figure 1). With this research, funded by the National Science Foundation, researchers can form highly conductive nanowire sheets within polymer blocks (Figure 2) or create a plethora of new conducting polymers.


Variations in the chemical "cap" also allow regioregular polythiophene strands to adhere directly to metal, silicon or other industrially important templates used in devices like transistors (Figure 3). They effectively self-assemble into a well-ordered, highly conducting nanoscale layers.

"The chain-growth method eliminates six production steps to create block co-polymer nanowires that conduct electricity a million times better than the all other conducting block copolymers," said McCullough.

Conducting polymers are remarkable materials that possess the electrical properties of metals yet retain the mechanical properties of polymers. In 1992 McCullough was the first to report the synthesis of regioregular polythiophenes, which in 2002 became the basis of a Carnegie Mellon spinout company, Plextronics, Inc.

The current research was conducted, in large part, by postdoctoral research fellows Malika Jeffries-El and Genevieve Sauve.

Block copolymers of regioregular polythiophenes conduct electricity so well due to their uniform composition and neat alignment into nanowires. Impurities and random orientation of polymer strands created by other methods vastly reduces their ability to conduct electricity, according to McCullough.

"A good analogy is a water hose. A bent hose transports water poorly, whereas a straight hose conducts water much more effectively. Likewise, irregularly shaped, disorganized polymers are poor conductors of electricity, whereas straight, stackable regioregular polythiophenes are excellent electrical conductors," said McCullough.

Regioregular polythiophenes have a wide range of potential applications, such as dissipating static electrical charges that build up on coated floors or use in disposable devices called radio frequency identification tags. (See www.plextronics.com for additional applications).

The superior conducting performance of regioregular polythiophenes is captured in their structure. Each polymer unit is composed of a chemical ring (thiophene) with a chemical branch on one side. Units are attached head to tail, so that all of the branches line up in one direction, much like feathers (Figure 4). The head-to-tail structure effectively straightens polythiophenes into rods that can be stacked one atop another.

To make a regioregular polythiophene polymer conductive, the scientists incorporate a pinch of a reactive additive to the polymer. This step removes some electrons from the forming polymer, thereby freeing the remaining electrons to move up and down the final polymer.

By attaching normal plastics to the polythiophene backbone, McCullough’s team can create nanowire stacks with versatile properties, such as softness and solubility in different fluids used in industrial manufacturing. Because their properties can be varied, regioregular conducting polymers have the widest range of commercial applications compared with any other conducting polymer, he said.


The Mellon College of Science at Carnegie Mellon University maintains innovative research and educational programs in biological sciences, chemistry, physics, mathematics and several interdisciplinary areas. For more information, visit http://www.cmu.edu/mcs.

Plextronics takes advantage of the vast commercial opportunities generated by these breakthroughs and has designed a new generation of matrials that enable broad market potential. For more information about Plextronics, Inc., please contact Jennifer Honig at jhonig@plextronics.com or 412-977-7703.

Lauren Ward | EurekAlert!
Further information:
http://www.cmu.edu/

More articles from Materials Sciences:

nachricht Decoding cement's shape promises greener concrete
08.12.2016 | Rice University

nachricht Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D
08.12.2016 | DOE/Brookhaven National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>