Featured Research

from universities, journals, and other organizations

Nanomaterials: Shedding light and water

Date:
August 20, 2012
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
Studies reveal a new way to make superhydrophobic surfaces with better self-cleaning capabilities.

Image of a natural lotus leaf surface with bumps in size of about ten micrometers and spikes of below one micrometer.
Credit: A*STAR

Studies reveal a new way to make superhydrophobic surfaces with better self-cleaning capabilities.

Related Articles


Many plants and animals have textured surfaces on their body for manipulating water. Some textured surfaces are designed, for example, to improve adhesion, while others may enable the collection of water from fog in arid regions. The lotus leaf, in particular, is the most widely cited example of having a textured surface with self-cleaning properties (see image).

The surface of the lotus leaf has a hierarchical structure -- comprising both micrometer and submicrometer features -- that makes it difficult for water droplets to spread. As a result, water droplets form tight spheres that easily roll off the leaf, picking up dirt particles en route. Such functionality can become useful if applied to textiles or windows, and may also be used in analytical techniques for controlling fluid flow.

Linda Yongling Wu at the A*STAR Singapore Institute of Manufacturing Technology and co-workers have now developed a fast and cost-efficient way to fabricate large-scale superhydrophopic surfaces on a hard material -- silica. The researchers used a laser to carve out a microstructured template that they then used to pattern a sol-gel coating. Nanoparticles were subsequently bound to the surface of the cured sol-gel surface to create a second level of hierarchy. The fabrication methodology can be adjusted to achieve different degrees of micro- and nanostructures.

In addition to the new fabrication methodology, Wu and co-workers considered various ways to optimize the water repellency of the textured surface. They found that increasing the surface roughness increases the true area of contact between the liquid and the solid, enhancing its intrinsic wetting properties. However, if the surface features are small enough, water can bridge protrusions leading to the formation of air pockets; the wettability of such a nanostructured material is then calculated as a weighted average of the wettability of the pure material and that of air. These two effects are known respectively as the Wenzel and Cassie-Baxter states.

The researchers derived an equation for calculating the surface contact angle between a water droplet and a silica surface with a certain degree of roughness. They found that there was a transition between the Wenzel to the Cassie-Baxter state, as surface structuring enters the nano dimension. The researchers found that for an optimum superhydrophobic effect, the Cassie-Baxter state must dominate the surface structure to allow a massive 83% of the surface state to be involved in air trapping with only 17% of the liquid drop surface actually in contact with the silica itself.

The researchers are hoping that their findings will generate new ideas for making innovative self-cleaning materials. "We are now developing the technology for real applications, such as easy-clean coating for solar films and structured surfaces for personal care products," says Wu.

The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technologies


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Linda Y. L. Wu, Q. Shao, X. C. Wang, H. Y. Zheng, C. C. Wong. Hierarchical structured sol–gel coating by laser textured template imprinting for surface superhydrophobicity. Soft Matter, 2012; 8 (23): 6232 DOI: 10.1039/C2SM25371B

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Nanomaterials: Shedding light and water." ScienceDaily. ScienceDaily, 20 August 2012. <www.sciencedaily.com/releases/2012/08/120820121230.htm>.
The Agency for Science, Technology and Research (A*STAR). (2012, August 20). Nanomaterials: Shedding light and water. ScienceDaily. Retrieved April 20, 2015 from www.sciencedaily.com/releases/2012/08/120820121230.htm
The Agency for Science, Technology and Research (A*STAR). "Nanomaterials: Shedding light and water." ScienceDaily. www.sciencedaily.com/releases/2012/08/120820121230.htm (accessed April 20, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, April 20, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Humanoid Robot Can Recognise and Interact With People

Humanoid Robot Can Recognise and Interact With People

Reuters - Innovations Video Online (Apr. 20, 2015) An ultra-realistic humanoid robot called &apos;Han&apos; recognises and interprets people&apos;s facial expressions and can even hold simple conversations. Developers Hanson Robotics hope androids like Han could have uses in hospitality and health care industries where face-to-face communication is vital. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Drones and Health Apps at Santiago's "Robotics Day"

Drones and Health Apps at Santiago's "Robotics Day"

AFP (Apr. 20, 2015) Latin American robotics experts gather in Santiago, Chile for "Robotics Day". Video provided by AFP
Powered by NewsLook.com
Japan Humanoid Robot Receives Customers at Department Store

Japan Humanoid Robot Receives Customers at Department Store

AFP (Apr. 20, 2015) She can smile, she can sing and she can give you guidance at one of the most upscale department stores in Tokyo...a female-looking humanoid makes her debut as a receptionist Video provided by AFP
Powered by NewsLook.com
Pee-Power Toilet to Light Up Disaster Zones

Pee-Power Toilet to Light Up Disaster Zones

Reuters - Innovations Video Online (Apr. 20, 2015) Students and staff are being asked to use a prototype urinal to &apos;donate&apos; urine to fuel microbial fuel cell (MFC) stacks that generate electricity to power lighting. The developers hope the pee-power technology will light toilet cubicles in refugee camps, where women are often at risk of assault in poorly lit sanitation areas. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins