Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

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

Microfluidics/Nanofluidics

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

News and information

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

New drug-delivery approach holds potential for treating obesity May 2nd, 2016

Graphene/ Graphite

Cooling graphene-based film close to pilot-scale production April 30th, 2016

University of Illinois researchers create 1-step graphene patterning method April 27th, 2016

Atomic magnets using hydrogen and graphene April 27th, 2016

Electrically Conductive Graphene Ink Enables Printing of Biosensors April 23rd, 2016

Govt.-Legislation/Regulation/Funding/Policy

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Making invisible physics visible: The Jayich Lab has created a new sensor technology that captures nanoscale images with high spatial resolution and sensitivity May 2nd, 2016

Clay nanotube-biopolymer composite scaffolds for tissue engineering May 1st, 2016

Chip Technology

Spintronics for future information technologies: Spin currents in topological insulators controlled May 2nd, 2016

Cooling graphene-based film close to pilot-scale production April 30th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Researchers create a first frequency comb of time-bin entangled qubits: Discovery is a significant step toward multi-channel quantum communication and higher capacity quantum computers April 28th, 2016

Discoveries

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

Non-animal approach to predict impact of nanomaterials on human lung published Archives of Toxicology publishes workshop recommendations May 2nd, 2016

Announcements

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

New drug-delivery approach holds potential for treating obesity May 2nd, 2016

Military

Making invisible physics visible: The Jayich Lab has created a new sensor technology that captures nanoscale images with high spatial resolution and sensitivity May 2nd, 2016

Nanograft seeded with 3 cell types promotes blood vessel formation to speed wound healing April 27th, 2016

The light stuff: A brand-new way to produce electron spin currents - Colorado State University physicists are the first to demonstrate using non-polarized light to produce a spin voltage in a metal April 26th, 2016

NRL reveals novel uniform coating process of p-ALD April 21st, 2016

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







Car Brands
Buy website traffic