Formation of ice requires a phase change. Generally this occurs easiest through heterogeneous transformations, ie it nucleates on a particle or surface. The wetting angle the water experiences at the solid/liquid interface drives the preferential decrease in required energy to nucleate into ice.

Modification of the surface of roads so that they are very hard to wet and hence the energy required for nucleation is higher.

Issues come about with any dirt may allow nucleation barrier to be dropped again, and I think once some Ice forms then it would quickly allow the rest of the water to nucleate.
-- lostmind, Jul 11 2012

This would be worse than the ice.
-- DIYMatt, Jul 11 2012


Would the final result be a propensity to remain wet until some trigger for sudden ice formation in a matter of seconds?
-- Ling, Jul 11 2012


This does has some practicality. Ice will still form, but breaking the bond between the road and the snow/ice allows for easier removal. That is basically all road salt does through brine formation.
-- AusCan531, Jul 11 2012


Hold on a second.

Reducing the wetting angle (ie, making the road hydrophobic) involves *decreasing* the surface energy, shirley? Wetting happens because the road-water interface has less surface energy than the surface of the road and of the water independently; raising surface energy of the road simply makes wetting more favourable. So you want to *lower* the road's surface energy.

Secondly, surface water is full of dust particles, which are more than adequate to nucleate ice formation, so a non-wettable surface won't really affect ice nucleation.

Thirdly, wetting releases energy as heat. Therefore, wetting actually _delays_ ice formation (very slightly) by warming the surface.

So, regrettably, I suspect that this idea has scored a hat-trick of wrongth.
-- MaxwellBuchanan, Jul 11 2012


It is my observation that most things that repel water are also slippery. We generally don't need that feature as part of a road surface. At least, not at this time. Perhaps, in the future, when everyone is driving vehicles that require a low-friction road surface....
-- Vernon, Jul 11 2012


We went through all of this last winter, didn't we? Something about a hydrophobic compound mixed with the asphalt medium, and there was another one about a road surface with billions of tiny dimples or something, and a couple of others involving channeled exhaust heat, and then [AusCan] and I had to explain to everyone what 'rock ice' is and why it's better to have the icy roads dry rather than wet... Does any of that sound familiar at all?
-- Alterother, Jul 11 2012


heterogenous nucleation energy is determined by

homogenous nucleation energy * function of wetting angle

function is 1 when wetting angle is 180 degrees

a wetting angle of 180 degrees is perfectly non- wetting
-- lostmind, Jul 12 2012


That wonderfully scientific description goes way over my gears 'n' guts head, but if you're suggesting wetting roads in winter conditions, forget it, my friend. It's a recipe for disaster at any angle.
-- Alterother, Jul 12 2012



random, halfbakery