Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nano-Cone Textures Generate Extremely "Robust" Water-Repellent Surfaces: Surfaces with differently shaped nanoscale textures may yield improved materials for applications in transportation, energy, and diagnostics

Side view scanning electron microscope image of a silicon surface textured with (a) cylindrical pillars and (b) nanocones.
Side view scanning electron microscope image of a silicon surface textured with (a) cylindrical pillars and (b) nanocones.

Abstract:
When it comes to designing extremely water-repellent surfaces, shape and size matter. That's the finding of a group of scientists at the U.S. Department of Energy's Brookhaven National Laboratory, who investigated the effects of differently shaped, nanoscale textures on a material's ability to force water droplets to roll off without wetting its surface. These findings and the methods used to fabricate such materials-published online October 21, 2013, in Advanced Materials-are highly relevant for a broad range of applications where water-resistance is important, including power generation and transportation.



High-speed video of droplets bouncing off a surface textured with nanocones.

Nano-Cone Textures Generate Extremely "Robust" Water-Repellent Surfaces: Surfaces with differently shaped nanoscale textures may yield improved materials for applications in transportation, energy, and diagnostics

Upton, NY | Posted on October 21st, 2013

"The idea that microscopic textures can impart a material with water-repellent properties has its origins in nature," explained Brookhaven physicist and lead author Antonio Checco. "For example, the leaves of lotus plants and some insects' exoskeletons have tiny-scale texturing designed to repel water by trapping air. This property, called 'superhydrophobicity' (or super-water-hating), enables water droplets to easily roll off, carrying dirt particles along with them."

Mimicking this self-cleaning mechanism of nature is relevant for a wide range of applications, such as non-fouling, anti-icing, and antibacterial coatings. However, engineered superhydrophobic surfaces often fail under conditions involving high temperature, pressure, and humidity-such as automotive and aircraft windshields and steam turbine power generators-when the air trapped in the texture can be prone to escape. So scientists have been looking for schemes to improve the robustness of these surfaces by delaying or preventing air escape.

Creating nanoscale textures

"In principle, the high robustness required for several applications could be achieved with texture features as small as 10 nanometers (billionths of a meter) because the pressure needed for liquid to infiltrate the texture and force the air out increases dramatically with shrinking texture size," explained Checco. "But in practice, it is difficult to shrink the surface texture features while maintaining control over their shape."

"For this work, we have developed a fabrication approach based on self assembly of nanostructures, which lets us precisely control the surface texture geometry over as large an area as we want-in principle, even as large as square meters," Checco said.

The procedure for creating these superhydrophobic nanostructured surfaces, developed in collaboration with scientists at Brookhaven's Center for Functional Nanomaterials (CFN), takes advantage of the tendency of "block copolymer" materials to spontaneously self-organize through a mechanism known as microphase separation. The self-assembly process results in polymer thin films with highly uniform, tunable dimensions of 20 nanometers or smaller. The team used these nanostructured polymer films as templates for creating nanotextured surfaces by combining with thin-film processing methods more commonly used in fabricating electronic devices, for example by selectively etching away parts of the surface to create textured designs.

"This new approach leverages our thin-film processing methods, in order to precisely tailor the surface nanotexture geometry through control of processing conditions," said Brookhaven physicist and co-author Charles Black.
The effect of shape

The scientists created and tested new materials with different nanoscale textures-some decorated with tiny straight-sided cylindrical pillars and some with angle-sided cones. They were also able to control the spacing between these nanoscale features to achieve robust water repellency.

After coating their test materials with a thin film of wax-like material, the scientists measured how water droplets rolled off each surface as they were tilted from vertical to flat positions and compared the behavior with that of untextured solids.

"While we fabricated several different nanotextures that all significantly increased the water repellency, certain shapes performed differently than others," said Brookhaven physicist and co-author Atikur Rahman. The enhanced water-repellency was consistent with earlier studies, including a previous one by Checco and collaborators that showed that air bubbles trapped in the textured surfaces force the water to ball up into drops [http://www.bnl.gov/newsroom/news.php?a=11085]. However, in the current study, the team further showed that cone-shaped nanostructures are significantly better than cylindrical pillars at forcing water droplets to roll off the surface, thus keeping surfaces dry.

"In the case of the cylindrical pillars, as the contact line of the droplet recedes on the textured surface, it can get pinned to the nanotexture, leaving behind a microscopic liquid layer on the pillars' flat tops instead of a perfectly dry substrate," Checco said. "The cone-shaped structures have smaller, pointed tops, likely preventing this effect."

The other important finding was that the water-repelling ability of cone-shaped nanotexturing held up even when water droplets were sprayed onto the surface with a pressurizing syringe. Such pressure could potentially force water into the nanosized pockmarks between the conical or cylindrical pillars, displacing the air bubbles and destroying the water-repelling effect.

The scientists monitored the splashing droplets using a high-speed camera capable of capturing 30,000 frames per second. For the cone-textured surface, "The sprayed droplets splash and eject satellite droplets that spread radially outward while the centermost portion of the original drop flattens out, then recoils, and bounces off the surface," Checco said. "We do not observe any pinned drops at the impact point after the drop has bounced back, indicating that the surface remains water-repellent during the impact at speeds up to 10 meters per second, which is faster than the speed of a falling raindrop."
Next steps

The team is working on extending this technique to other materials, including glass and plastics, and on fabricating surfaces that are also oil-repellent by further tweaking the feature shape.

They are also studying the resistance of different nanotextures to water penetration using intense beams of x-rays available at Brookhaven's National Synchrotron Light Source (NSLS). "The goal is to understand quantitatively how the forced liquid infiltration depends on the texture size and geometry. This will assist the design of even more resilient superhydrophobic coatings," Checco said.

The nanopatterning technique used in this study also enables the design of a wide variety of materials with different texturing-and therefore different water-repelling properties-on different parts of a single surface. This approach could be used, for example, to fabricate nanoscale channels with self-cleaning and low fluid friction properties for diagnostic applications such sensing the presence of DNA, proteins, or biotoxins.

"This result is an excellent example of the type of project that can be done collaboratively with the DOE's Nanoscale Science Research Centers," said Black. "Previously, we have been pursuing similar structures for an entirely different scientific purpose. We are happy to work with Antonio through the CFN User program to help him accomplish his research goals."

This research was funded by the DOE Office of Science.

Brookhaven Science Associates (BSA), the company that manages Brookhaven Lab for the Department of Energy, has filed a U.S. Provisional Patent Application for this technology. For information about licensing the technology from BSA, contact Kimberley Elcess, , (631) 344-4151.

The Center for Functional Nanomaterials is one of five DOE Nanoscale Science Research Centers (NSRCs), national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit science.energy.gov.

The National Synchrotron Light Source (NSLS) provides intense beams of infrared, ultraviolet, and x-ray light for basic and applied research in physics, chemistry, medicine, geophysics, and environmental and materials sciences. Supported by the Office of Basic Energy Sciences within the U.S. Department of Energy, the NSLS is one of the world's most widely used scientific facilities. For more information, visit www.nsls.bnl.gov.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov

####

About Brookhaven National Laboratory
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

For more information, please click here

Contacts:
Karen McNulty Walsh
(631) 344-8350

or
Peter Genzer
(631) 344-3174

Copyright © Brookhaven National Laboratory

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 Links

Scientific paper: "Robust Superhydrophobicity in Large Area Nanostructured Surfaces Defined by Block Copolymer Self Assemby":

Previous research: Scientists Glimpse Nanobubbles on Super Non-Stick Surfaces:

Related News Press

News and information

New quantum phenomena in graphene superlattices September 18th, 2017

Do titanium dioxide particles from orthopedic implants disrupt bone repair? September 16th, 2017

Hydrogen power moves a step closer: Physicists are developing methods of creating renewable fuel from water using quantum technology September 15th, 2017

Corrosion in real time: UCSB researchers get a nanoscale glimpse of crevice and pitting corrosion as it happens September 14th, 2017

Arrowhead Hosts Investor & Analyst R&D Day to Introduce TRiM(TM) Platform and Lead RNAi-based Drug Candidates September 14th, 2017

Laboratories

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Ames Laboratory scientists move graphene closer to transistor applications August 30th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Landscapes give latitude to 2-D material designers: Rice University, Oak Ridge scientists show growing atom-thin sheets on cones allows control of defects August 9th, 2017

Videos/Movies

Researchers printed graphene-like materials with inkjet August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Govt.-Legislation/Regulation/Funding/Policy

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Magnetic cellular 'Legos' for the regenerative medicine of the future September 12th, 2017

First on-chip nanoscale optical quantum memory developed: Smallest-yet optical quantum memory device is a storage medium for optical quantum networks with the potential to be scaled up for commercial use September 11th, 2017

High-speed quantum memory for photons September 9th, 2017

Self Assembly

Physicists gain new insights into nanosystems with spherical confinement: Enormous potential for the targeted delivery of pharmaceutical agents and the creation of tailored nanoparticles July 27th, 2017

Oddball enzyme provides easy path to synthetic biomaterials May 17th, 2017

Nanotubes that build themselves April 14th, 2017

Nanocages for gold particles: what is happening inside? March 16th, 2017

Nanomedicine

Do titanium dioxide particles from orthopedic implants disrupt bone repair? September 16th, 2017

Arrowhead Hosts Investor & Analyst R&D Day to Introduce TRiM(TM) Platform and Lead RNAi-based Drug Candidates September 14th, 2017

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Applications for the nanomedTAB are open until September 18th, 2017 September 13th, 2017

Discoveries

New quantum phenomena in graphene superlattices September 18th, 2017

Do titanium dioxide particles from orthopedic implants disrupt bone repair? September 16th, 2017

Hydrogen power moves a step closer: Physicists are developing methods of creating renewable fuel from water using quantum technology September 15th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Materials/Metamaterials

New quantum phenomena in graphene superlattices September 18th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Corrosion in real time: UCSB researchers get a nanoscale glimpse of crevice and pitting corrosion as it happens September 14th, 2017

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Announcements

New quantum phenomena in graphene superlattices September 18th, 2017

Do titanium dioxide particles from orthopedic implants disrupt bone repair? September 16th, 2017

Hydrogen power moves a step closer: Physicists are developing methods of creating renewable fuel from water using quantum technology September 15th, 2017

Corrosion in real time: UCSB researchers get a nanoscale glimpse of crevice and pitting corrosion as it happens September 14th, 2017

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

New quantum phenomena in graphene superlattices September 18th, 2017

Do titanium dioxide particles from orthopedic implants disrupt bone repair? September 16th, 2017

Hydrogen power moves a step closer: Physicists are developing methods of creating renewable fuel from water using quantum technology September 15th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Energy

Insect eyes inspire new solar cell design from Stanford August 31st, 2017

The power of perovskite: OIST researchers improve perovskite-based technology in the entire energy cycle, from solar cells harnessing power to LED diodes to light the screens of future electronic devices and other lighting applications August 18th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Two Scientists Receive Grants to Develop New Materials: Chad Mirkin and Monica Olvera de la Cruz recognized by Sherman Fairchild Foundation August 16th, 2017

Automotive/Transportation

More durable, less expensive fuel cells: University of Delaware researchers have developed a new technology that could speed up the commercialization of fuel cell vehicles September 5th, 2017

High-tech electronics made from autumn leaves: New process converts biomass waste into useful electronic devices August 30th, 2017

Nanoparticles pollution rises 30 percent when flex-fuel cars switch from bio to fossil: Study carried out in São Paulo, home to the world's largest flex fuel urban fleet, shows increase of ultrafine particulate matter when ethanol prices rose and consumption fell August 28th, 2017

2-faced 2-D material is a first at Rice: Rice University materials scientists create flat sandwich of sulfur, molybdenum and selenium August 14th, 2017

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