Laser Technique Transforms Metals into Extremely Water-Repellent Materials

Extremely water-repellent, or super-hydrophobic, materials are desirable for applications like rust prevention and anti-icing. However, most current hydrophobic materials rely on chemical coatings. Scientists at the University of Rochester have used lasers to transform metals into super-hydrophobic materials without the need for temporary coatings. Their powerful and precise laser-patterning technique creates an intricate pattern of micro- and nanoscale structures to give the metals their new properties. This work builds on earlier research by the team in which they used a similar laser-patterning technique that turned metals black. The researchers say the technique creates multifunctional surfaces that are not only super-hydrophobic but also highly absorbent optically. The materials are much more slippery than Teflon, a common hydrophobic material that often coats nonstick frying pans.

Transcript

00:00:06 A couple years ago, my lab created a technology that turns a variety of materials superhydrophilic. Superhydrophilic means it actually attracts water. We actually turned the surface hydrophilic to such a strong degree that water runs uphill against gravity. That technology can have many applications on its own. After that, we started to work on the counterpart technology, making surface to repel water or as we call it, hydrophobic. We have been working on creating superhydrophobic material using a laser processing technique. What we see here is pretty interesting. The water falls to wards the surface and is repelled and bounces off the surface. This is achieved by creating a unique pattern of surface structures at micro and nano scales with our laser processing technology and those structures are intrinsically part of the material’s surface. Most of the hydrophobic surfaces available today rely on chemical coatings.

00:01:24 Our surface has many advantages over the coatings out there. First our surface has a much stronger hydrophobic effect than the coatings and secondly, we don’t have to worry about coatings peeling off and the surface degrading over time. Many people think of Teflon as a strong hydrophobic material. However, if you want to get rid of water on a Teflon surface you have to tilt the surface to about 70 degrees before the water starts to slide off slowly. Our surface requires an extremely small angle, if at all, for water to slide off. I think there are many possible applications for this new superhydrophobic surface. For instance, if a surface repels water, you will also prevent icing on the surface, you will be anti-corrosive and there’s sanitation applications as well. We wanted to create this superhydrophobic surface that will not only repel water but also repels water containing a waste materials. We know

00:02:40 in many developing countries in the world, clean water is a scarce resource so if you create a toilet instead of using a lot of water to flush the toilet, would require little or no water but still stay clean and dry.