Universities claim ‘green’ DWR development is a match for the best
17/12/2015
A material made by scientists at Rice University in Houston, the University of Swansea in Wales, the University of Bristol in England and the University of Nice Sophia Antipolis in France is inexpensive, non-toxic and can be applied to a variety of surfaces via spray- or spin-coating, the team of researchers has said.
Led by Rice chemist Andrew Barron they have reported the findings in the American Chemical Society journal, ACS Applied Materials and Interfaces.
The hydrocarbon-based material may be a “green” replacement for fluorocarbon-based durable water-resistant (DWR) solutions, Professor Barron said.
“Nature knows how to make these materials and stay environmentally friendly,” he added. “Our job has been to figure out how and why, and to emulate that. In the lotus leaf, there are papillae within the epidermis and epicuticular waxes on top. In our material, there is a microstructure created by the agglomeration of alumina nanoparticles mimicking the papillae and hyper-branched organic moieties simulating the effect of the epicuticular waxes.”
Fabrication and testing of what the researchers call a branched hydrocarbon low-surface energy material (LSEM) were carried out by Shirin Alexander, a research officer at the Energy Safety Research Institute at Swansea.
To be “superhydrophobic”, a material has to have a water contact angle larger than 150 degrees. Contact angle is the angle at which the surface of the water meets the surface of the material. The higher the angle, the greater the beading. An angle of zero degrees is, basically a puddle, the research team said, while a maximum angle of 180 degrees defines a sphere just touching the surface.
The research team’s LSEM, with an observed angle of about 155 degrees, is equivalent to the best fluorocarbon-based superhydrophobic coatings, Professor Barron said. Even with varied coating techniques and curing temperatures, the material retained its qualities.
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