My daughter Clem and I spent some time recently playing with “magic sand”: super-hydrophobic powder from Educational Innovations. It is a compelling demonstration, but we hadn’t many good ideas about applications. Just today, though, I saw that Oak Ridge National laboratory in the US have developed a new super-hydrophobic coating, which can be made cheaply (from powdered glass) and applied over large surfaces.
The thing that attracted me was the description of how the nano-structured material “maintains a microscopic layer of air on surfaces even when submerged in water, resulting in a profound change in the basic water-solid interface”. The inventor, John Simpson likes to refer to this as the “Moses effect” – and I love the name! He also speculates about how such a layer could significantly reduce the drag experienced by a ship moving through water, potentially saving a lot of energy.
There’s more… Another feature of this powder is its thermal insulation. Water does not enter the grain pores because the powder grains are superhydrophobic. This results in a dry breathable coating with trapped insulating air throughout. And, because the powder consists almost entirely of porous amorphous silica, it also makes a very good electrical insulator. In addition, since the powder creates a layer of air between the coated substrate and any water on the surface, water-based corrosion of the substrate is greatly reduced or entirely eliminated.
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