Water Repellent

It may not be so much a substance as the small-scale texture involved. Waxy coatings can cause water to bead up; roughening the surface the right amount will enhance the effect. And then there's SERIOUS water-repelling: see Hydrophobicity. I'm thinking that this article needs to be posted on its own - in fact, that's why I was on the home page just now!

Read an article a few years back about this. The micro-texture on leaves keeping the water beaded as well as shedding dust. Researchers were trying to replicate the effect in automotive paints. Would be pretty cool to have a car that never needed washing!

There is an article here on GlobalSpec about it for an umbrella. Check this like link out.

http://cr4.globalspec.com/blogentry/1330

MidniteFighter

The superhydrophobic glass compound is interesting but I am interested in a compound that I see in plants, can that compound be isolated and synthesised or extracted or does it work because it's part of a living organism?

Thanks for all the comments. It's structure, not chemistry that prevents the leaf from penetrating the surface tension of the bead of water? So I'm looking for micro structures.

Structure of surface is one part of water repelling.

The other part is paraffin (for example C25H52 or in general for n Carbon atoms (C) there are 2n+2 hydrogen atoms in a molekule.

In chemistry these are called alkanes.

These are gases if low C, liquids (kerosene) if medium C count and solids (at room temperature) if n is above 12 or 14.

This material is chemically extremely stable except when burning.

So the biological material (the wax on the surface of apples and plums) is not degraded at rot but is deposited with carbon rich material: brown coal.

From this it is extracted by distilling.

Try it and dissolve some in benzene and apply to wood or paper and let evaporate the benzene: a highly water repellant coating will result.

For most technical applications this material is too soft, so the polymerised (very high n) form = polyethylene is used and if this is not good enough (hot water tubing) crosslinked PE will be good for more than 100°C and considerable pressure.

The next better can be Teflon: same carbon structure but hydrogen atoms replaced by fluorine.

RHABE

From my day's long ago in Agriculture school I seem to remember something about "Tricomes ?" the little hairs on the leaf surface having something to do with the water beading on some types of leaves. You may want to check out this Wikipedia reference. http://en.wikipedia.org/wiki/Lotus_effect.

Hope this helps out, Mike