- Number 309 |
- April 12, 2010
Nanobubbles yield super non-stick surfaces
Optical profile of a water
drop (center) on “nanopitted”
silicon with a scanning
electron micrograph of the
nanocavities (right) and an
illustration of the nanobubble’s
shape as inferred from x-ray
measurements. (Click image
for larger version.)
Want to create a super non-stick surface? Pock mark a smooth material with cavities measuring billionths of a meter. These nanocavities trap tiny bubbles which render the surface extremely water repellent, say researchers at DOE's Brookhaven Lab, who recently captured the first glimpse of these miniscule air bubbles. Their work 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.
The water-shedding effect, called “superhydrophobicity,” occurs when air bubbles remain trapped in the textured surface, drastically reducing the area of liquid in contact with the solid. This forces the water to ball up into drops that readily roll off.
To glimpse the nanoscale air bubbles, the scientists created a regular array of more than a trillion nanocavities on an otherwise flat surface, coated it with a wax-like surfactant, and watched how x-rays diffracted off the surface. The measurements revealed air bubbles measuring about 10 nanometers in diameter (ten thousand times smaller than the width of a single human hair) that kept water from penetrating any more than 5 to 10 nanometers into the cavities. This coated, nanotextured surface was much more water repellant than the flat surface alone, with features that make it attractive for a wide range of applications.
Full story link: http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=1085
[Karen McNulty Walsh, 631.344.8350,
kmcnulty@bnl.gov]