Unexpected adhesion properties of graphene may lead to new nanotechnology devices

Aug 23, 2011
This is an artist's rendering of an array of pressurized graphene membranes. A CU-Boulder team recently discovered that graphene has surprisingly high adhesion properties, findings that may help lead to the development of new graphene-based mechanical devices like gas separation membranes. Credit: Illustration courtesy Victor Tzen and Rex Tzen.

Graphene, considered the most exciting new material under study in the world of nanotechnology, just got even more interesting, according to a new study by a group of researchers at the University of Colorado Boulder.

The new findings -- that graphene has surprisingly powerful adhesion qualities -- are expected to help guide the development of graphene manufacturing and of graphene-based such as resonators and membranes, according to the CU-Boulder team. The experimentsshowed that the extreme flexibility of graphene allows it to conform to the topography of even the smoothest substrates.

Graphene consists of a single layer of chemically bonded in a hexagonal chicken wire lattice. Its unique could some day replace silicon as the basis of electronic devices and because of its remarkable electrical, mechanical and thermal properties, said Assistant Professor Scott Bunch of the CU-Boulder mechanical engineering department and lead study author.

A paper on the subject was published online in the Aug. 14 issue of Nature Nanotechnology. Co-authors on the study included CU-Boulder graduate students Steven Koenig and NarasimhaBoddeti and Professor Martin Dunn of the mechanical engineering department.

"The real excitement for me is the possibility of creating new applications that exploit the remarkable flexibility and adhesive characteristics of graphene and devising unique experiments that can teach us more about the nanoscale properties of this amazing material," Bunch said.

Not only does graphene have the highest electrical and among all materials known, but this "wonder material" has been shown to be the thinnest, stiffest and strongest material in the world, as well as being impermeable to all standard gases. It's newly discovered adhesion properties can now be added to the list of the material's seemingly contradictory qualities, said Bunch.

The CU-Boulder team measured the adhesion energy of graphene sheets, ranging from one to five atomic layers, with a glass substrate, using a pressurized "blister test" to quantify the adhesion between graphene and glass plates.

Adhesion energy describes how "sticky" two things are when placed together. Scotch tape is one example of a material with high adhesion; the gecko lizard, which seemingly defies gravity by scaling up vertical walls using adhesion between its feet and the wall, is another. Adhesion also canplay a detrimental role, as in suspended micromechanical structures where adhesion can cause device failure or prolong the development of a technology, said Bunch.

The CU research, the first direct experimental measurements of the adhesion of graphene nanostructures, showed that so-called "van der Waals forces" -- the sum of the attractive or repulsive forces between molecules -- clamp the graphene samples to the substrates and also hold together the individual graphene sheets in multilayer samples.

The researchers found the adhesion energies between graphene and the glass substrate were several orders of magnitude larger than energies in typical micromechanical structures, an interaction they described as more liquid-like than solid-like, said Bunch.

The CU-Boulder study was funded primarily by the National Science Foundation and the Defense Advanced Research Projects Agency.

The importance of graphene in the scientific world was illustrated by the 2010 Nobel Prize in physics that honored two scientists at Manchester University in England, Andre K. Geim and Konstantin Novoselov, for producing, isolating, identifying and characterizing graphene.

There is interest in exploiting graphene's incredible mechanical properties to create ultrathin membranes for energy-efficient separations such as those needed for natural gas processing or water purification, while graphene's superior electrical properties promise to revolutionize the microelectronics industry, said Bunch.

In all of these applications, including any large-scale graphene manufacturing, the interaction that has with a surface is of critical importance and a scientific understanding will help push the technology forward, he said.

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User comments : 9

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NotAsleep
4.3 / 5 (6) Aug 23, 2011
The obligatory comment: Is there anything graphene can't do???

If we replace everything in our lives with graphene and it then becomes the new asbestos, I'm just going to sit in the woods with a bottle of rum on a cold day and wait for the end. Too many things are being proven too good to be true...
Palli
5 / 5 (4) Aug 23, 2011
The obligatory comment: Is there anything graphene can't do???

If we replace everything in our lives with graphene and it then becomes the new asbestos, I'm just going to sit in the woods with a bottle of rum on a cold day and wait for the end. Too many things are being proven too good to be true...

Graphene can't drink rum with you in the woods. But I like your plan :)
NotAsleep
5 / 5 (3) Aug 23, 2011
Not yet it can't...
poof
2.4 / 5 (7) Aug 23, 2011
So if we put sheets of this along the border we can catch mexicans for pennies on the dollar!
MachinegunDojo
5 / 5 (1) Aug 23, 2011
nano-scale bubblewrap. The world shall soon end.
fmfbrestel
5 / 5 (1) Aug 23, 2011
So it is super tough, super thin, can act like glue and can carry a current. All we need is roll to roll processing and you can say hello to nano-composite wires, ribbons, or sheets that will revolutionize materials science.

Not that roll to roll processing will be simple (far from it) but when it happens, hold on to your socks. :-)

Parsec
5 / 5 (1) Aug 24, 2011
So it is super tough, super thin, can act like glue and can carry a current. All we need is roll to roll processing and you can say hello to nano-composite wires, ribbons, or sheets that will revolutionize materials science.

Not that roll to roll processing will be simple (far from it) but when it happens, hold on to your socks. :-)


If your socks are made from graphene you won't be able to let go of them! Think of it, socks that work like gecko feet!
bishop
not rated yet Aug 24, 2011
What a wonder material it is... GO GRAPHENE!!!
KomMaelstrom
1 / 5 (1) Aug 27, 2011
I'm not sure one material is any more useful than another, we just have a limited understanding of the possible ways in which to manipulate our environment. So our systems are only advantageous of specific physical properties.

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