Wednesday, August 29, 2018 by Edsel Cook
The U.S. Navy wants a slick new material that can shed any liquid or semi-liquid that comes into contact with it. When applied as a coating to the hulls of ships and submarines, the “omniphobic” material will immensely reduce friction drag, allowing the sea-going craft to travel faster without using as much energy or fuel, an article in Science Daily reported.
The material is being developed by a University of Michigan (UM) team under Dr. Anish Tuteja. They are working on creating a chemical coating that is transparent, tough, will stick to all kinds of surfaces, and repels almost all liquids.
Omniphobic coatings have caught the Navy’s attention due to the way they are able to reduce friction drag. Anything that travels through liquids like water will encounter resistance that bogs it down, forcing it to expend more effort or energy to keep moving or to increase speed.
“A significant percentage of a ship’s fuel consumption [up to 80 percent at lower speeds and 40-50 percent at higher speeds] goes toward maintaining its speed and overcoming friction drag,” explained Ki-Han Kim, a program officer with the Office of Naval Research (ONR) of the U.S. Navy.
He believes that greatly decreasing the effect of friction drag would allow ships to travel much faster and further while also conserving battery power or fuel. (Related: Harnessing static electricity? Invention makes self-powered devices possible, without batteries.)
The UM-developed omniphobic material promises to solve the problem of friction drag. If applied to the hull of a ship, water will be unable to actually touch it. Instead, the liquid will bead up and slide away from the hull.
Repellent coatings are usually specialized to resist only a few types of liquids. Furthermore, it is difficult to create one that will also stick to the surface of an object for a long period of time.
Teflon is a good example of the capabilities and limitations of phobic coatings. When water ends up on a Teflon-coated surface, it will bead up and roll off the pan.
However, oil will spread across the non-stick surface since it has different properties from water. Teflon can also be scratched off the surface of the pan.
“Researchers may take a very durable polymer matrix and a very repellent filler and mix them,” Tuteja said about omniphobic materials. “But this doesn’t necessarily yield a durable, repellent coating. Different polymers and fillers have different miscibilities.”
Miscibility is the ability of two different substances to combine with each other. Tuteja said that this made the process of creating a composite material much more complicated than just mixing together the most durable ingredients one could find.
Tuteja and his team pored over computer databases in search of the molecular properties of different chemical substances. They then entered that data into math equations that predicted the behavior of the resulting blend.
The UM researchers went through hundreds of possible chemical combinations before stumbling upon their winning formula. Laboratory trials confirmed the potency of the mixture.
The new omniphobic coating has the texture of rubber. It can be brushed, dipped, spin-coated, or sprayed onto various surfaces.
It binds very firmly with the surface it is applied on. It is also able to resist damage from the kind of rough treatment that comes with everyday use. Last but not least, the coating is transparent.
The omniphobic coating’s application is not just limited to waterproofing the hulls of ships and submarines. Tuteja suggested that it can also serve as a weatherproofing coating for delicate, expensive equipment.
Visit FutureScienceNews.com for more articles on new materials that can change the way we live.