Navigation Links
How 'transparent' is graphene?
Date:12/4/2012

CAMBRIDGE, Mass. -- The amazing electrical, optical and strength properties of graphene, a single-atom-thick layer of carbon, have been extensively researched over the last decade. Recently, the material has been studied as a coating that might confer electrical conductivity while maintaining other properties of the underlying material.

But the "transparency" of such a graphene coating to wetting a measure of the degree to which liquids spread out or bead up on a surface is not as absolute as some researchers had thought. New research at MIT shows that for materials with intermediate wettability, graphene does preserve the properties of the underlying material. But for more extreme cases superhydrophobic surfaces, which intensely repel water, or superhydrophilic ones, which cause water to spread out an added layer of graphene does significantly change the way coated materials behave.

That's important, because these extreme cases are generally of greatest interest. For example, coating a superhydrophobic material with graphene was seen as a possible way of making electronic circuits that would be protected from short-circuiting and corrosion in water. But it's not quite that simple, the new research shows.

The findings were recently published in the journal Physical Review Letters by professors Daniel Blankschtein and Michael Strano, graduate student Chih-Jeh Shih, and three other MIT postdocs and students.

Blankschtein, the Herman P. Meissner '29 Professor of Chemical Engineering, has studied wetting properties for a long time. He had not previously examined graphene, but decided to explore its wettability now that it's a material of great interest to researchers.

Because graphene's transparency to wettability turned out not to be perfect, Blankschtein says, "this finding may be viewed as a negative result." But, he adds, "it is nevertheless extremely important to the scientific community, because it [shows] what can actually be accomplished in practice."

Most electrically conductive materials, he points out, are hydrophilic: Water spreads readily on them, thoroughly wetting the surface. "On the other hand," he says, "for many electronic and military applications, it is important to fabricate hydrophobic, electrically conductive surfaces." And while graphene's transparency to wettability is not perfect, it may still be good enough for such applications, he says.

This research, which included both theoretical modeling and experimental confirmation, shows that by depositing a large graphene sheet, grown by a process called chemical vapor deposition, on another material's surface, "it would be possible to induce electrical conductivity on the surface, while partially preserving the desired surface wetting behavior," Blankschtein says. In fact, he adds, the contact angle of such a surface the measure of how well it prevents wetting "is believed to be one of the highest attainable on a flat, electrically conductive surface to date."

Shih, the lead author of the paper, says, "We have demonstrated that the wettability of a transparent, graphene-coated surface can be manipulated without undermining its thermal/electrical conductivity." That's useful because "in general, conductive surfaces have very high wettability due to their high surface tension, and it is generally very challenging to produce a thermally/electrically conductive surface with tunable wettability" wettability that can be controlled almost at will.

The team describes this partial transmission of the underlying characteristics as "translucency," rather than transparency, of wettability.

By selecting a particular combination of an underlying material with a graphene coating, different combinations of electrical, optical and wetting characteristics can be achieved, Shih says: "People can control the wetting properties of the substrate this breakthrough successfully decouples the conductivity and wettability of a material."

What's more, this opens up new possibilities for practical devices, because the materials involved are already widely used in industry, Shih says: "Due to its compatibility with today's semiconductor processes, many exciting opportunities may be pursued in the areas of microelectronics, nanoscale heat transfer and microfluidic devices to simultaneously engineer desired wettability, heat transfer and electronic transport."

Blankschtein emphasizes that in addition to the potential applications, "I'm excited about this from a fundamental point of view." It shows, he says, that "you can't assume that you can just take a substrate and drop graphene on it without perturbing the wetting behavior." By understanding this complex behavior, "we can learn how to take advantage of that."


'/>"/>
Contact: Caroline McCall, MIT Media Relations
cmccall5@mit.edu
Massachusetts Institute of Technology
Source:Eurekalert

Related biology technology :

1. Transparent material breakthrough
2. UCLA team develops highly efficient method for creating flexible, transparent electrodes
3. Transparent memory chips are coming
4. Quantum bar magnets in a transparent salt
5. ScaleMatrix Leads the Way Unveiling the Industry’s First Transparent Pricing Tool in Private Cloud Offerings
6. Lotus leaf inspires fog-free finish for transparent surfaces
7. Graphene? From any lab!
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/16/2017)... 2017  Windtree Therapeutics, Inc. (Nasdaq: ... aerosolized KL4 surfactant therapies for respiratory diseases, announced ... showed that aerosolized KL4 surfactant reduced lung inflammation ... animal model. The Company believes that these preclinical ... that supports the role of KL4 surfactant as ...
(Date:2/15/2017)... ... February 15, 2017 , ... Executive ... Chief Commercial Officer with GenePeeks. Matt is a veteran life sciences and ... computational genomics company focused on identifying inherited disease risk in future generations. In ...
(Date:2/15/2017)... WASHINGTON, Feb. 15, 2017  Vanda Pharmaceuticals Inc. ... results for the fourth quarter and full year ... an exceptional year for Vanda as we continued ... and secured long-term exclusivity for Fanapt," said Mihael ... addition, our emerging pipeline with important 2017 milestones ...
(Date:2/15/2017)... ... February 15, 2017 , ... Diameter Health (Diameter) ... Health technology in the hands of Lantana analysts. The high-performance platform of Diameter ... public health entities – all those mining value from clinical data – to ...
Breaking Biology Technology:
(Date:2/7/2017)... BEACH, New York , February 7, 2017 /PRNewswire/ ... known as ID Global Solutions Corporation [OTC: IDGS], ("Ipsidy" ... identity management and electronic transaction processing services, is pleased ... reorganization of the Company. Effective January 31, ... of the Board of Directors, CEO and President.  An ...
(Date:2/2/2017)... , Feb. 2, 2017  EyeLock LLC, a market ... new white paper " What You Should Know About ... of ensuring user authenticity is a growing concern. In ... of users. However, traditional authentication schemes such as username/password ... Biometric authentication offers an elegant solution to the ...
(Date:1/26/2017)... Jan. 26, 2017  Crossmatch, a leading provider of ... solution aimed at combatting fraud, waste and abuse in ... at the Action on Disaster Relief conference in ... for UN agencies and foreign assistance organizations throughout ... and abuse are a largely unacknowledged problem in the ...
Breaking Biology News(10 mins):