Water-Repellent Nanotechnology

We received a number of requests about what nanotechnology can do to help repel water. From where? How about the windshield of a car?

To start off, think about a drop of water. Put a drop of water on a piece of paper and it will get sucked up by the paper. Put a drop of water on a piece of wax paper and it will stay as a drop. Some materials are hydrophilic meaning that they like water, others are hydrophobic meaning that they hate water (if you have hygrophobia that is something different, that is a fear of water). It has to do with the chemistry of the surface. Wax is made up of chemicals that don’t like water. Sometimes you can make a material hydrophobic or hydrophilic by just treating it in a special way. Plastics can be treated with different things to give you materials that repel water or attract water. For example, some researchers in Korea are looking at a plastic (Polyethylene Terephthalate or PET) and can make water form drops or spread out. One material that can be made hydrophobic or hydrophilic.

Nature has evolved a number of different ways to make things hydrophobic or hydrophilic. Lotus leaves have tiny hairs that are only a few hundred nanometers in size. These hairs are hydrophobic and help to bead up water, and when the bead gets big enough it forms a drop and rolls down the leaf. Think about driving in a car through the mist, the water seems to stick to the window. Only when the bead of water gets big enough does it roll down the window.

There are also beetles found in Namibia, a country in Africa that is right next to the Atlanta Ocean. While there is a lot of water, it is salt water and so most plants and animals can drink it. The Namibia beetle has evolved to collect water on its back. It also has tiny little bumps of hydrophobic material that helps it collect water. When the drop of water gets big enough it slides down the back of the beetle and the beetle gets a drink.