Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > How 'transparent' is graphene? MIT researchers find that adding a coating of graphene has little effect on how a surface interacts with liquids - except in extreme cases

A simulated water droplet on a sheet of suspended graphene.
Image: Chih-Jen Shih
A simulated water droplet on a sheet of suspended graphene.

Image: Chih-Jen Shih

Abstract:
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.

How 'transparent' is graphene? MIT researchers find that adding a coating of graphene has little effect on how a surface interacts with liquids - except in extreme cases

Cambridge, MA | Posted on December 3rd, 2012

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."

The work, which also involved MIT postdocs Qing Hua Wang, Shangchao Lin and Zhong Jin and graduate student Kyoo-Chul Park, was supported by the Office of Naval Research, the National Science Foundation and MIT's Institute for Soldier Nanotechnology.

####

For more information, please click here

Contacts:
Caroline McCall
MIT Media Relations

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Hiden Release New Gas Analysis Catalogue August 21st, 2014

Wyatt Technology’s 24th International Light Scattering Colloquium to Highlight Developments in Applications and Characterization of Nanoparticles August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

Graphene

Graphene may be key to leap in supercapacitor performance August 20th, 2014

Ultrasonic Waves Applied in Production of Graphene Nanosheets August 20th, 2014

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

New test reveals purity of graphene: Rice, Osaka scientists use terahertz waves to spot contaminants August 13th, 2014

Could hemp nanosheets topple graphene for making the ideal supercapacitor? August 12th, 2014

Microfluidics/Nanofluidics

Novel chip-based platform could simplify measurements of single molecules: A nanopore-gated optofluidic chip combines electrical and optical measurements of single molecules onto a single platform August 14th, 2014

Blacktrace Holdings Ltd. to in-license PerkinElmer Technology August 8th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Chip Technology

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

AI Technology (AIT) Introduces Novel High Temperature Large Area Underfill with Proven Stress Absorption August 15th, 2014

Iranian Scientists Stabilize Protein on Highly Stable Electrode Surface August 14th, 2014

Discoveries

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

Nanotechnology Helps Production of Super Adsorbent Polymers August 21st, 2014

Rice physicist emerges as leader in quantum materials research: Nevidomskyy wins both NSF CAREER Award and Cottrell Scholar Award August 20th, 2014

Announcements

Wyatt Technology’s 24th International Light Scattering Colloquium to Highlight Developments in Applications and Characterization of Nanoparticles August 21st, 2014

Ultra-short pulse lasers & Positioning August 21st, 2014

Malvern’s Dr Alan Rawle talks TLAs in plenary lecture at Particulate Systems Analysis conference August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

Military

New material could enhance fast and accurate DNA sequencing August 13th, 2014

On the frontiers of cyborg science August 10th, 2014

Advanced thin-film technique could deliver long-lasting medication: Nanoscale, biodegradable drug-delivery method could provide a year or more of steady doses August 6th, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE