Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Elliot Scientific now representing Raman Imaging specialists WITec in the UK and Eire - Unique correlative analysis in one instrument: Raman/AFM, Raman/SNOM December 10th, 2018

A new 'spin' on kagome lattices: Team's findings shed new light on the presence of spin-orbit coupling and topological spin textures in kagome lattices December 9th, 2018

Milestone for bERLinPro: Photocathodes with high quantum efficiency December 8th, 2018

Harnessing the power of 'spin orbit' coupling in silicon: Scaling up quantum computation December 7th, 2018

Graphene/ Graphite

These small caps are tapping a graphene market that has more than doubled in a year December 1st, 2018

Study unlocks full potential of 'supermaterial' graphene: Researchers remove silicon contamination from graphene to double its performance November 30th, 2018

Researchers create new 'smart' material with potential biomedical, environmental uses November 23rd, 2018

Epoxy compound gets a graphene bump: Rice scientists combine graphene foam, epoxy into tough, conductive composite November 14th, 2018

The National Graphene Association Is Excited To Announce A New Affiliate Partnership With Graphene Engineering Innovation Centre (GEIC) November 7th, 2018

Microfluidics/Nanofluidics

WSU researchers develop new technique to understand biology at the nanoscale November 7th, 2018

UT engineers develop first method for controlling nanomotors: Breakthrough for nanotechnology as UT engineers develop first method for switching the mechanical motion of nanomotors September 21st, 2018

NIST Researchers Simulate Simple Logic for Nanofluidic Computing June 30th, 2018

Govt.-Legislation/Regulation/Funding/Policy

A new 'spin' on kagome lattices: Team's findings shed new light on the presence of spin-orbit coupling and topological spin textures in kagome lattices December 9th, 2018

It's not a shock: Better bandage promotes powerful healing November 29th, 2018

French Researchers Extend Reach of Mass Spectrometry with Nanomechanical Resonators: Neutral Mass Spectrometry’ Fills Gap In Existing Weighing Technologies November 27th, 2018

Three CEA Projects Awarded European Research Council Synergy Grants November 26th, 2018

Chip Technology

A new 'spin' on kagome lattices: Team's findings shed new light on the presence of spin-orbit coupling and topological spin textures in kagome lattices December 9th, 2018

Harnessing the power of 'spin orbit' coupling in silicon: Scaling up quantum computation December 7th, 2018

CEA-Leti’s RRAM-based TCAM Circuits Meet Requirements of Multicore Neuromorphic Processors December 5th, 2018

Nanoscribe Presents Successor Model Photonic Professional GT2 for High-Resolution 3D Microfabrication: The first ever production of structures in millimeter size with micrometer precision December 4th, 2018

Discoveries

A new 'spin' on kagome lattices: Team's findings shed new light on the presence of spin-orbit coupling and topological spin textures in kagome lattices December 9th, 2018

Milestone for bERLinPro: Photocathodes with high quantum efficiency December 8th, 2018

Harnessing the power of 'spin orbit' coupling in silicon: Scaling up quantum computation December 7th, 2018

Iran Develops Water-Repellent Nano-Paint December 5th, 2018

Announcements

Elliot Scientific now representing Raman Imaging specialists WITec in the UK and Eire - Unique correlative analysis in one instrument: Raman/AFM, Raman/SNOM December 10th, 2018

A new 'spin' on kagome lattices: Team's findings shed new light on the presence of spin-orbit coupling and topological spin textures in kagome lattices December 9th, 2018

Milestone for bERLinPro: Photocathodes with high quantum efficiency December 8th, 2018

Harnessing the power of 'spin orbit' coupling in silicon: Scaling up quantum computation December 7th, 2018

Military

Bending light around tight corners without backscattering losses: New photonic crystal waveguide based on topological insulators paves the way to build futuristic light-based computers November 19th, 2018

'Smart skin' simplifies spotting strain in structures: Rice U. invention can use fluorescing carbon nanotubes to reveal stress in aircraft, structures November 15th, 2018

Epoxy compound gets a graphene bump: Rice scientists combine graphene foam, epoxy into tough, conductive composite November 14th, 2018

Unlocking the Secrets of Metal-Insulator Transitions: X-ray photon correlation spectroscopy at NSLS-II's CSX beamline used to understand electrical conductivity transitions in magnetite November 8th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project