Tuning graphene film so it sheds water

Feb 01, 2011

Windshields that shed water so effectively that they don't need wipers. Ship hulls so slippery that they glide through the water more efficiently than ordinary hulls.

These are some of the potential applications for graphene, one of the hottest in the field of , raised by the research of James Dickerson, assistant professor of physics at Vanderbilt.

Dickerson and his colleagues have figured out how to create a freestanding film of graphene oxide and alter its so that it either causes to bead up and run off or causes it to spread out in a thin layer.

"Graphene films are transparent and, because they are made of carbon, they are very inexpensive to make," Dickerson said. "The technique that we use can be rapidly scaled up to produce it in commercial quantities."

His approach is documented in an article published online by the journal ACS Nano on Nov. 26.

Graphene is made up of sheets of arranged in rings – something like molecular chicken wire. Not only is this one of the thinnest materials possible, but it is 10 times stronger than steel and conducts electricity better at room temperature than any other known material. Graphene's exotic properties have attracted widespread scientific interest, but Dickerson is one of the first to investigate how it interacts with water.

Many scientists studying graphene make it using a dry method, called "mechanical cleavage," that involves rubbing or scraping graphite against a hard surface. The technique produces sheets that are both extremely thin and extremely fragile. Dickerson's method can produce sheets equally as thin but considerable stronger than those made by other techniques. It is already used commercially to produce a variety of different coatings and ceramics. Known as electrophoretic deposition, this "wet" technique combines an electric field within a liquid medium to create nanoparticle films that can be transferred to another surface.

Dickerson and his colleagues found that they could change the manner in which the graphene oxide particles assemble into a film by varying the pH of the liquid medium and the electric voltage used in the process. One pair of settings lay down the particles in a "rug" arrangement that creates a nearly atomically smooth surface. A different pair of settings causes the particles to clump into tiny "bricks" forming a bumpy and uneven surface. The researchers determined that the rug surface causes water to spread out in a , while the brick surface causes water to bead up and run off.

Dickerson is pursuing an approach that could create film that enhances these water-associated properties, making them even more effective at either spreading out water or causing it to bead up and run off. There is considerable academic and commercial interest in the development of coatings with these enhanced properties, called super-hydrophobic and super-hydrophilic. Potential applications range from self-cleaning glasses and clothes to antifogging surfaces to corrosion protection and snow-load protection on buildings. However, effective, low-cost and durable coatings have yet to make it out of the laboratory.

Dickerson's idea is to apply his basic procedure to "fluorographene" – a fluorinated version of graphene that is a two-dimensional version of Teflon – recently produced by Kostya S. Novoselov and Andre K. Geim at the University of Manchester, who received the 2010 Nobel Prize for the discovery of graphene. Normal fluorographene under tension should be considerably more effective in repelling water than oxide. So there is a good chance a "brick" version and a "rug" version would have extreme water-associated effects, Dickerson figures.

Explore further: Atom-thick CCD could capture images: Scientists develop two-dimensional, light-sensitive material

Related Stories

Super-thin carbon sheets poised to revolutionize electronics

Mar 02, 2009

Super-thin films of carbon with exotic properties, now taking the scientific world by storm, may soon mean a new era of brighter, faster, and smaller computers, smart phones, and other consumer electronics. Brighter digital ...

Recommended for you

The simplest element: Turning hydrogen into 'graphene'

Dec 16, 2014

New work from Carnegie's Ivan Naumov and Russell Hemley delves into the chemistry underlying some surprising recent observations about hydrogen, and reveals remarkable parallels between hydrogen and graphene ...

User comments : 21

Adjust slider to filter visible comments by rank

Display comments: newest first

axemaster
3.3 / 5 (6) Feb 01, 2011
"Windshields that shed water so effectively that they don't need wipers."

If you know even basic Newtonian mechanics, you know that this is a bunch of garbage... you'd want to have wipers even for a frictionless surface.
nuge
3 / 5 (1) Feb 01, 2011
I've heard of ideas for these sorts of hydrophilic/hydrophobic materials before, but the cheapness of graphene makes this seem more promising. The applications sound pretty cool.
Justsayin
4.3 / 5 (4) Feb 01, 2011
How about a scuba diving mask that does not fog up ever.
ibuyufo
1 / 5 (1) Feb 01, 2011
They should put graphene sheet on ice! Ice skating would rise to another level. And is there nothing that graphene can't do???
denial
5 / 5 (1) Feb 01, 2011
In 1985 3M created a very slick surface for boat hulls. It was applied to an America's Cup yacht in Perth, AU and it was almost immediately outlawed by the IYRU. The ban is still in effect for this type of use. The use of graphene for ocean going vessels won't work because of marine growth. The current paints work because they are ablative.
lexington
1 / 5 (7) Feb 01, 2011
It'll never work. Graphene is full of holes where the water would go through.
FrankHerbert
0.7 / 5 (48) Feb 01, 2011
It'll never work. Graphene is full of holes where the water would go through.


lmao you're stupid
MorituriMax
4 / 5 (2) Feb 01, 2011
How about we actually make one of these ideas into an actual product, I've heard so much about graphene over the last couple years, but not an iota of actual product.

It's really starting to feel like I'm coming to a science-FICTION library of neat new things to put into stories than physics making everyone's life better.
lexington
1 / 5 (5) Feb 01, 2011
It'll never work. Graphene is full of holes where the water would go through.


lmao you're stupid


Try build a toy boat out of chicken wire if you don't believe me.
LivaN
4 / 5 (2) Feb 02, 2011
It'll never work. Graphene is full of holes where the water would go through.


lmao you're stupid


Try build a toy boat out of chicken wire if you don't believe me.


How about using chicken wire with holes smaller than the size of water molecules. Would that work?
antialias
2 / 5 (1) Feb 02, 2011
Damn...a few weeks ago I posted that I thought graphene does about anything nowadays but clean the kitchen sink...and now it does that too!

This stuff is just amazing.

(As for the chicken wire. You can build a boat out of chicken wire quite easily of you use enough layers in a good configuration.)
Foolish1
3 / 5 (1) Feb 02, 2011
"Windshields that shed water so effectively that they don't need wipers."

If you know even basic Newtonian mechanics, you know that this is a bunch of garbage... you'd want to have wipers even for a frictionless surface.


You would be surprised. There is trick rainex available commercially I remember using years ago. For about a week after you apply it water just beads off in the rain and you don't need to run your wipers. Until it wears off it is crazy.

I suspect the ability of surfaces to have magical properties will be practically hampered by the amount of mud and grime covering them :(
yoatmon
4.5 / 5 (2) Feb 02, 2011
"...it is 10 times stronger than steel..."
Sorry to have to correct you but the tensile strength of graphene exceeds that of steel by more than factor 200 (established in 2009). (remove brackets prior to ref. to following link)
(http://)en.wikipedia.org/wiki/Graphene
Most recent research determined the exact tensile strength on the nano scale to be 217x that of steel.
yoatmon
4.5 / 5 (2) Feb 02, 2011
@ lexington:
"It'll never work. Graphene is full of holes where the water would go through."
Actually, it would work perfectly. The space between the bonded carbon atoms is so small that it is even impossible for hydrogen to penetrate the lattice structure. A water molecule (H2O) is much larger than a hydrogen molecule.
wizatron
4 / 5 (2) Feb 02, 2011
So, windshields will be able to repel water but without wipers what will remove mud, tar, grime and bugs. It looks like graphene is still an answer looking for a problem.
Cal_Sailor
not rated yet Feb 02, 2011
The hydrophobic qualities sound exactly like what I would want on my old racing sailboat! However, the sea critters that like to grow on my bottom will probably like graphene just as much. I guess it would be too much to hope that graphene have antifouling properties.
Caliban
1 / 5 (1) Feb 02, 2011
The most useful transportation application will be as a coating on aircraft, eliminating icing, and the associated fuel efficiency/maneuverability/safety losses due to ice buildup.

Only thing stated in the article that worries me is the process -I don't like to hear of flourine-intensive chemical manufacturing, as it generally creates toxic byproducts. Still, with proper safeguards, no reason why those byproducts couldn't be reprocessed to eliminate those risks.

That's probably being rather blindly optimistic, though.
Crischoi
not rated yet Feb 03, 2011
I am not sure how many people read the ACS article but CA (contact angle) 79 is NOT hydrophobic. Although the authors claimed the CA can be potentially increased but the current mehtod is quite limited for the proposed application.
yoatmon
not rated yet Feb 03, 2011
@ Caliban:
"I don't like to hear of flourine-intensive chemical manufacturing"
If the tenor of the article - published by RICE in the following link - can be wholly trusted, your apprehensions are superfluous.
(remove = signs prior to ref. the following link)
==http://www.==media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=15053
Caliban
not rated yet Feb 03, 2011
@ Caliban:
"I don't like to hear of flourine-intensive chemical manufacturing"
If the tenor of the article - published by RICE in the following link - can be wholly trusted, your apprehensions are superfluous.
(remove = signs prior to ref. the following link)
==http://www.==media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=15053


@yoatman

Your link is for Rice University's News and Media webpage. Were you tring to link an article?

Update. found your article, but I don't see anything to indicate fluorene use has been rendered harmless, or really, any of the other processes described. Do you know something that I'm not seeing?
yoatmon
not rated yet Feb 03, 2011
@ Caliban:
Perhaps you missed this passage?

"For pristine graphene, Sun started with a thin film of poly (methyl methacrylate) (PMMA) -- perhaps best known in its commercial guise as Plexiglas -- spun onto a copper substrate that acted as a catalyst. Under heat and low pressure, flowing hydrogen and argon gas over the PMMA for 10 minutes reduced it to pure carbon and turned the film into a single layer of graphene. Changing the gas-flow rate allowed him to control the thickness of the PMMA-derived graphene."

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.