Cheap graphene film used for self-cleaning glass
A team at Vanderbilt University has found a way of using graphene to create windshields that don't need wipers.
Assistant professor of physics James Dickerson and his colleagues have figured out how to create a freestanding film of graphene oxide and alter its surface roughness, so that it either causes water to bead up and run off or makes it spread out in a thin layer.
Other applications include super-efficient hulls for ships, self-cleaning glasses and clothes, antifogging surfaces, corrosion protection and snow-load protection on buildings.
"Graphene films are transparent and, because they are made of carbon, they are very inexpensive to make," Dickerson said. "The technique that we use can be rapidly scaled up to produce it in commercial quantities."
Dickerson produces his graphene via electrophoretic deposition, which can produce sheets just as thin but much stronger than those made by other techniques. It's already used commercially to produce a variety of different coatings and ceramics, and combines an electric field within a liquid medium to create nanoparticle films that can be transferred to another surface.
Dickerson and his colleagues found that they could change the way in which the graphene oxide particles assemble into a film by varying the pH of the liquid medium and the electric voltage used in the process.
One pair of settings lays down the particles in a 'rug' arrangement that creates a nearly atomically smooth surface. A different pair causes the particles to clump into tiny "bricks" forming a bumpy and uneven surface.
The rug surface causes water to spread out in a thin layer, while the brick surface makes it bead up and run off.
Dickerson believes he can enhance these properties, making them even more effective at either spreading out water or causing it to bead up and run off. He wants to apply his basic procedure to fluorographene – a fluorinated version of graphene that is a two-dimensional version of Teflon - which should have even more extreme water-repelling properties.