"Superomniphobic" Nanoscale Coating Repels Almost Any Liquid 104
cylonlover writes "A team of engineering researchers at the University of Michigan has developed a nanoscale coating that causes almost all liquids to bounce off surfaces treated with it. Creating a surface structure that is least 95 percent air, the new 'superomniphobic' coating is claimed to repel the broadest range of liquids of any material in its class, opening up the possibility of super stain-resistant clothing, drag-reducing waterproof paints for ship hulls, breathable garments that provide protection from harmful chemicals, and touchscreens resistant to fingerprint smudges."
Re:Comparison to Neverwet (Score:5, Informative)
All this superhydrophobic stuff is mostly just silicone.
The main difference is how it's applied and what type of structure it forms. As I understand it RainX is mostly just a simple silicone coating where the idea is to just smooth out the windshield (in the theory that on a completely smooth surface, water is more likely to bead than whet). NeverWet is a silicone nano-particles suspended in a spray/solvent. When the solvent evaporates, it makes a somewhat uniform coating of nano-particles of silicone.
Apparently in this technique, they apply silicone with electrospinning [wikipedia.org] instead of run-of-the-mill spray-n-dry techniques. The main difference is that with electrospinning it is accomplished w/o w/o solvents and the result can be made into a very uniform nano-structure. There's also no solvent to ruin whatever you need to apply it to. Of course figuring out the right technique to create a specific nano-structure that works as you intend it isn't an accomplishment to be sneezed at (not that it would stick anyhow)...
Re:Yet another miracle nano-coating (Score:5, Informative)
Every x months for the past 5 years I hear about some new super-coating that repels dirt, water, oil etc.. Every time I'm like, "cool, when will it come standard on new cars?" I hate having to wash my car every few days (it's parked outside) or it starts looking like crap.
I suppose when I get a flying car, that's when I'll finally see this miracle coating in action.
Posting anonymously because of a personal connection to research some of these materials, but I think it's worth it to quickly clear up a few uncertainties I see in the comments already posted:
1) The reason you don't see this stuff all over is that these materials are expensive and usually not durable. Nanoscale patterns can be created through a variety of approaches, some of which are a bit more complicated but can repair or recreate their surface patterns after abrasion. As you might expect, the materials that can recreate their surface patterns tend to be on the more expensive end of the scale.
2) The past 5 years have seen major progress in *phobic materials. We're getting closer to cost effective, more durability, and even better phobicity, but we're still not there.
3) Superhydrophobic isn't the same as omniphobic. Generally surfaces will either have a high contact angle with water OR with nonpolar liquids. Superhydrophobic means the contact between a droplet of water and the material will be extremely small. Omniphobic means the surface repels both polar and nonpolar liquids.
4) Nanoscale patterning of a surface can also lead to superhydrophilicity, the opposite of superhydrophobicity. The mechanism for this isn't fully understood.
Re:Exterior coating for condoms? (Score:2, Informative)
I work in a porno shop and probably get laid way more than the entirety of the /. population combined.
Re:Comparison to Neverwet (Score:4, Informative)
This coating is actually not just silicone, but a blend of silicone and " liquid-resisting nanoscale cubes developed by the Air Force that contain carbon, fluorine, silicon and oxygen," which is apparently supposed to be layman's terms for fluorodecyl polyhedral oligomeric silsequioxane (POSS). Those are cubic networks of silica that have a fluorocarbon chain at each vertex, sort of a three-dimensional Teflon. The very low chemical reactivity plus the nanoscale roughness of the surface causes the lotus effect. [wikipedia.org] The mixture with silicone helps the POSS adhere to materials, though they state in their paper that the POSS preferentially segregates to the surface and is responsible for the coating's properties:
"A wide range of organic chemicals including toluene and chloroform, which readily wet/swell cross-linked PDMS, are also easily repelled. Even when our surfaces are immersed in a liquid bath of PDMS (Mn = 800 Da, lv = 19.8 mN/m), a plastron (air pockets) layer that is indicative of a robust Cassie–Baxter state is formed. The plastron layer was stable and remained unchanged even upon extended exposure to un-cross-linked PDMS. Note that PDMS is a major constituent of the electrospun beads. The observation of a stable plastron layer even when the surface is submerged under PDMS is extremely unique and indicates that the surface does not reconfigure, even when exposed to an enthalpically favorable solvent."
Re:ugly words! (Score:5, Informative)
phobicity? ...philicity?
weren't phobia and ...philia good enough already?
Foophobia is the fear or hatred of foo. Foophobicity is the degree of fear or hatred of foo.