Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Glimpse Nanobubbles on Super Non-Stick Surfaces

26.02.2010
Could lead to design of water-shedding materials for applications in energy, medicine, and more

Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have obtained the first glimpse of miniscule air bubbles that keep water from wetting a super non-stick surface. Detailed information about the size and shape of these bubbles — and the non-stick material the scientists created by “pock-marking” a smooth material with cavities measuring mere billionths of a meter — is being published online today in the journal Nano Letters.

“Our results explain how these nanocavities trap tiny bubbles which render the surface extremely water repellent,” said Brookhaven physicist and lead author Antonio Checco. The research could lead to a new class of non-stick materials for a range of applications, including improved-efficiency power plants, speedier boats, and surfaces that are resistant to contamination by germs.

Non-stick surfaces are important to many areas of technology, from drag reduction to anti-icing agents. These surfaces are usually created by applying coatings, such as Teflon, to smooth surfaces. But recently — taking the lead from observations in nature, notably the lotus leaf and some varieties of insects — scientists have realized that a bit of texture can help. By incorporating topographical features on surfaces, they’ve created extremely water repellant materials.

“We call this effect ‘superhydrophobicity,’” said Brookhaven physicist Benjamin Ocko. “It occurs when air bubbles remain trapped in the textured surfaces, thereby drastically reducing the area of liquid in contact with the solid.” This forces the water to ball up into pearl shaped drops, which are weakly connected to the surface and can readily roll off, even with the slightest incline.

“To get the first glimpse of nanobubbles on a superhydrophobic surface we created a regular array of more than a trillion nano-cavities on an otherwise flat surface, and then coated it with a wax-like surfactant,” said Charles Black, a physicist at Brookhaven’s Center for Functional Nanometerials.

This coated, nanoscale textured surface was much more water repellant than the flat surface alone, suggesting the existence of nanobubbles. However, because the nanoscale is not accessible using ordinary microscopes, little is known about these nanobubbles.

To unambiguously prove that these ultra-small bubbles were present, the Brookhaven team carried out x-ray measurements at the National Synchrotron Light Source. “By watching how the x-rays diffracted, or bounced off the surface, we are able to image extremely small features and show that the cavities were mostly filled with air,” said Brookhaven physicist Elaine DiMasi.

Checco added, “We were surprised that water penetrates only about 5 to 10 nanometers into the cavities — an amount corresponding to only 15 to 30 layers of water molecules — independent of the depth of the cavities. This provides the first direct evidence of the morphology of such small bubbles.”

According to the scientists’ observations, the bubbles are only about 10 nanometers in size — about ten thousand times smaller than the width of a single human hair. And the team’s results conclusively show that these tiny bubbles have nearly flat tops. This is in contrast to larger, micrometer-sized bubbles, which have a more rounded top.

“This flattened configuration is appealing for a range of applications because it is expected to increase hydrodynamic slippage past the nanotextured surface,” Checco said. “Moreover, the fact that water hardly penetrates into the nano-textures, even if an external pressure is applied to the liquid, implies that these nanobubbles are very stable.”

Therefore, in contrast to materials with larger, micrometer-sized textures, the surfaces fabricated by the Brookhaven team may exhibit more stable superhydrophobic properties.

“These findings provide a better understanding of the nanoscale aspects of superhydropobicity, which should help to improve the design of future superhydrophobic non-stick surfaces,” Checco said.

This research is funded by the DOE Office of Science. Tommy Hofmann, a former Brookhaven physicist now at Helmholtz Zentrum Berlin, also contributed to this work.

Karen McNulty Walsh | EurekAlert!
Further information:
http://www.bnl.gov

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>