Researchers at Northwestern University and Princeton
University have created a new kind of polymer that, because of its
extraordinary thermal and mechanical properties, could be used in
everything from airplanes to solar cells.
The polymer, a nanocomposite that incorporates functionalized,
exfoliated graphene sheets, even conducts electricity, and researchers
hope to use that property to eventually create thermally stable,
optically transparent conducting polymers.
The results of their research were published May 11 in the
online version of Nature Nanotechnology.
Researcher at the McCormick School of Engineering originally
teamed up with researchers at Princeton several years ago. McCormick
researchers had experience working with polymer nanocomposites, and
Princeton researchers had developed a way to exfoliate, or split apart,
graphite sheets into very thin single layer, surface-functionalized
Previous use of graphite in polymers did not garner
significantly improved properties since researchers could never get the
graphite exfoliated. That meant the graphite was rigid with a low
surface area and could only minimally impact properties of the polymer.
But when researchers put even a small amount the newly
exfoliated graphene sheets — enough to equal only .05 percent
of the material — into the polymer, they found the graphene
changed the polymer’s thermal stability temperature by 30
degrees. Even adding graphene sheets equal to .01 percent of the
material increased stiffness by 33 percent — far beyond what
researchers had predicted. The drastic changes in both the thermal
stability and the stiffness after adding just a tiny percentage of
functionalized graphene indicated that the graphene changes large
regions of the polymer radiating out from the nanoparticle surfaces in
a percolating network structure.
The new polymer nanocomposite based on graphene also exhibited
the same or superior thermal and mechanical properties as using
functionalized single-wall nanotubes in polymer — but was
much easier and cheaper to create.
“This is the first time people have been able to
demonstrate dramatically altered properties like this with really small
quantities of graphite-based materials,” says Cate Brinson,
Jerome B. Cohen Professor of Mechanical Engineering and corresponding
author of the paper.
The graphene sheets also will inherently be able to block
moisture and gases from penetrating the material as well as change the
thermal stability temperature and improve mechanical properties, making
the durable polymer a candidate for use in everything from aircrafts to
sports equipment to solar cells
“I think it has enormous potential,”
Brinson says. “With the ready availability of graphite and
the properties we have demonstrated, this new material will enable
significant structural scale use of carbon-based
Next researchers are studying the polymer’s
electroconductivity, quantifying and optimizing the results with the
goal of creating optically transparent conducting polymers that are