Re: Query regarding glass surfaces? - Anti fog products?

Gas Bag wrote:

Green

Thanks for your reply?..and all the others. I?m well aware there are
a whole variety of anti-fog liquids/gels/waxes available. In fact
there?s a particular brand that I use for masks/goggles - it?s
absolutely amazing, and I swear by it. (I?m more than happy to let
you know, but I don?t want to seem like an advertisement for them)
But what I?m trying to do is achieve a permanent effect that is 100%
effective; there already is some technology out there that does
exactly that. Take a look:

http://www.abc.net.au/ra/innovations/stories/s1213247.htm

As fogging on glass/plastic surfaces is caused by water?s surface
tension, I thought perhaps a very slightly rough surface might help
break the surface tension of the tiny water droplets. I?m guessing
probably not, but there?s no harm in asking.

If it is a hydrated silicate surface you monolayer it with a reactive
silane, RSiX3. -X is typically -OMe or -Cl. R is typically a three
atom spacer then a quaternized ammonium with counterion. That
drastically reduces the surface tension and water sheets not fogs.
Presumably a PEO or poly(vinylpyrrolidinone) oligomer tail would also
the job.

Rain-X takes the opposite tack. Now R is a silicone oligomer and the
treated surface is hyperhydrophobic. Water violently beads but a
breeze blows it off. Very nice for windshields - your wipers glide
across the surface if you need them at all. After treatment, lightly
burnish the surface, wipe with rubbing alcohol, and burnish again.
That gets rid of most of the residual goo.

One wonders why competition swimmers don't "condition" their skin with
hydrophobes. Uncoupling the otherwise wetted surface would
substantially decrease friction.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
.

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