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

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Copper shines as flexible conductor August 29th, 2014

Microfluidics/Nanofluidics

Nanoscale assembly line August 29th, 2014

Graphene

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Graphene Structure Studied in Iran by Novel Method August 25th, 2014

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

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

Govt.-Legislation/Regulation/Funding/Policy

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Leading European communications companies and research organizations have launched an EU project developing the future 5th Generation cellular mobile networks August 28th, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

Chip Technology

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

Fonon Announces 3D Metal Sintering Technology: Emerging Additive Nano Powder Manufacturing Technology August 28th, 2014

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Discoveries

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

Copper shines as flexible conductor August 29th, 2014

Announcements

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

Nanoscale assembly line August 29th, 2014

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Military

Fonon Announces 3D Metal Sintering Technology: Emerging Additive Nano Powder Manufacturing Technology August 28th, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

Introducing the multi-tasking nanoparticle: Versatile particles offer a wide variety of diagnostic and therapeutic applications August 26th, 2014

Biomimetic photodetector 'sees' in color: Rice lab uses CMOS-compatible aluminum for on-chip color detection August 25th, 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