Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Water theory is watertight, researchers say

19.01.2007
There may be tiny bubbles in the wine, but not at the interface between water and a waxy coating on glass, a new study shows.

The behavior of water when placed in contact with hydrophobic (water-repellent) surfaces, such as raincoats and freshly waxed cars, has puzzled scientists for a long time. According to a controversial theoretical prediction, water near a hydrophobic surface will pull away and leave a thin layer of depleted water at the surface – that is, water molecules at the interface will pack less tightly than usual.

Now, a team of researchers at the University of Illinois at Urbana-Champaign and Argonne National Laboratory has resolved the controversy. Using near-perfect hydrophobic surfaces and synchrotron X-ray measurement techniques, the researchers found the theoretical prediction to be correct. They report their findings in the Dec. 31 issue of the journal Physical Review Letters.

"Previous experiments have been interpreted sometimes in favor of a depletion layer, sometimes against, and sometimes as indicating intimate solid-water contact in places and 'nanobubbles' in others," said Steve Granick, a professor of materials science and engineering, chemistry and physics at Illinois.

"Part of our study was to help understand why there was so much disagreement in the scientific literature," said Granick, who also is a researcher at the Frederick Seitz Materials Research Laboratory on campus and at the university's Beckman Institute for Advanced Science and Technology.

To study the nature of hydrophobicity, the researchers first prepared a nearly ideal hydrophobic surface – a self-assembled methyl-terminated octadecylsilane monolayer. Then they made synchrotron X-ray measurements of the interface between water and monolayer.

The measurements revealed a depletion layer, about one water molecule in thickness. The depletion layer was present with and without air dissolved in the water. Because no nanobubbles were seen, bubbles must not play a significant role in hydrophobicity, the researchers conclude.

The synchrotron X-ray data "unambiguously confirm the theoretical expectation that water, when it meets a planar hydrophobic surface, forms a depletion layer," the researchers write.

"We found that in a real system – more complicated that the theory assumes – the theory does capture the essence," Granick said. "The next time I see water beading on a raincoat, my vision of how the water molecules experience that raincoat is going to be different."

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

More articles from Physics and Astronomy:

nachricht New research could literally squeeze more power out of solar cells
20.04.2018 | University of Warwick

nachricht Atoms may hum a tune from grand cosmic symphony
20.04.2018 | University of Maryland

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: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Scientists re-create brain neurons to study obesity and personalize treatment

20.04.2018 | Health and Medicine

Spider silk key to new bone-fixing composite

20.04.2018 | Materials Sciences

Clear as mud: Desiccation cracks help reveal the shape of water on Mars

20.04.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>