Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'Bottlebrush' polymers make dielectric elastomers increasingly viable for use in devices

10.11.2016

A multi-institutional research team has developed a new electroactive polymer material that can change shape and size when exposed to a relatively small electric field. The advance overcomes two longstanding challenges regarding the use of electroactive polymers to develop new devices, opening the door to a suite of applications ranging from microrobotics to designer haptic, optic, microfluidic and wearable technologies. The work was performed by researchers at North Carolina State University, the University of North Carolina at Chapel Hill, Carnegie Mellon University and the University of Akron.

"Dielectric elastomers are the most responsive electroactive polymers in terms of achievable strains, but two big hurdles have effectively prevented the smart materials community from using them in commercial devices," says Richard J. Spontak, Distinguished Professor of Chemical and Biomolecular Engineering and professor of materials science and engineering at NC State, who co-authored a paper describing the new materials.


This image shows electrical response of a circular diaphragm composed of a pure bottlebrush elastomer upon electroactuation with increasing voltage and without any external pre-strain. The numbers indicate the electric field-induced area expansion under constant-volume conditions at room temperature.

Credit: Richard Spontak

"First, previous dielectric elastomers required large electric fields in order to trigger actuation, or movement -- on the order of at least 100 kilovolts per millimeter (kV/mm). With our new material, we can see actuation at levels as low as ca. 10 kV/mm."

"The second challenge is that, previously, materials had to be pre-strained," Spontak says. "This would either mean using a frame to physically strain the material, or adding a second component to the polymer to retain the strain after it was applied. But our material consists of a single component that is specifically designed at the molecular level to inherently possess pre-strain. In other words, we don't need a frame or a second component - our material is ready to be used as soon as it is cross-linked into a specific shape."

The new material that has permitted this breakthrough is a "bottlebrush" silicone elastomer, which has been engineered to possess these unique properties, and it is not difficult to manufacture.

"We are working specifically with bottlebrush polymers, which are prepared by grafting long polymeric side chains to a polymer backbone," says Sergei S. Sheiko, George A. Bush, Jr. Distinguished Professor of Chemistry at UNC and corresponding author of the paper.

"The resulting molecules may be viewed as filaments that are thick, yet remain quite flexible, which allows for significant reduction of the materials' rigidity and makes them more stretchable. Furthermore, the mechanical properties can be controlled by varying the bottlebrush architecture - for example, by preparing molecules with different degrees of polymerization of grafted chains and different grafting densities.

"This architectural control of mechanical properties has reduced the limit of stiffness in dry polymer materials by 1,000 times, demonstrated extensibility of up to eight times, and opened up new applications not available to stiffer materials or materials with liquid fractions," Sheiko says. "One of these applications -- their use as free-standing dielectric elastomers - has been demonstrated, which we discuss in this paper."

"We're at the earliest stages of identifying all the potential ways in which we could use this new class of material," Spontak says. "It works better than anticipated, and now we're beginning to consider potential applications."

###

The paper, "Bottlebrush Elastomers: A New Platform for Freestanding Electroactuation," is published in the journal Advanced Materials. Lead author of the paper is Mohammad Vatankhah-Varnoosfaderani, a postdoctoral researcher at UNC. The paper was co-authored by William F. M. Daniel, Alexandr P. Zhushma, Qiaoxi Li and Benjamin J. Morgan of UNC; Daniel P. Armstrong of NC State; Krzysztof Matyjaszewski of Carnegie Mellon; and Andrey V. Dobrynin of the University of Akron. The work was done with support from the National Science Foundation under grants DMR 1122483, DMR 1407645, DMR 1436201 and DMR 1409710, and from Becton Dickinson Technologies.

Media Contact

Matt Shipman
matt_shipman@ncsu.edu
919-515-6386

 @NCStateNews

http://www.ncsu.edu 

Matt Shipman | EurekAlert!

More articles from Materials Sciences:

nachricht Let the good tubes roll
19.01.2018 | DOE/Pacific Northwest National Laboratory

nachricht Method uses DNA, nanoparticles and lithography to make optically active structures
19.01.2018 | Northwestern University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | 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

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>