Cooltech: a nanoscale foglifter and frost inhibitor coating

From the American Chemical Society, something interesting.

A new anti-frost and anti-fog coating for glass

In an advance toward glass that remains clear under the harshest of conditions, scientists are reporting development of a new water-repellant coating that resists both fogging and frosting. Their research on the coating, which could have uses ranging from automobile windshields to camera lenses, appears in the journal ACS Nano.

Michael F. Rubner, Robert E. Cohen and colleagues point out that anti-fogging coatings that absorb water have been the focus of attention lately because of their ability to reduce light scattering and the resultant distortion caused by condensation. However, under extreme fogging conditions, these surfaces may frost and become foggy. They set out to make a better coating to withstand the aggressive conditions.

Their report describes development and testing of a new coating that rapidly absorbs water molecules that cannot freeze in the coating. At the same time, the coating has a water-repelling or hydrophobic effect to larger water droplets. The hydrophobic character means that water droplets do not spread extensively on the coating but essentially remain as flattened droplets.

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The authors acknowledge funding from the Samsung Scholarship and the Materials Research Science and Engineering Centers (MRSEC) Program of the National Science Foundation.

The paper (which I had to dig up since it wasn’t included in the press release, sigh….) is here:

Zwitter-Wettability and Antifogging Coatings with Frost-Resisting Capabilities

Abstract:

Antifogging coatings with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, under aggressive fogging conditions, these surfaces may exhibit frost formation or excess and nonuniform water condensation, which results in poor optical performance of the coating. In this paper, we show that a zwitter-wettable surface, a surface that has the ability to rapidly absorb molecular water from the environment while simultaneously appearing hydrophobic when probed with water droplets, can be prepared by using hydrogen-bonding-assisted layer-by-layer (LbL) assembly of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). An additional step of functionalizing the nano-blended PVA/PAA multilayer with poly(ethylene glycol methyl ether) (PEG) segments produced a significantly enhanced antifog and frost-resistant behavior. The addition of the PEG segments was needed to further increase the nonfreezing water capacity of the multilayer film. The desirable high-optical quality of these thin films arises from the nanoscale control of the macromolecular complexation process that is afforded by the LbL processing scheme. An experimental protocol that not only allows for the exploration of a variety of aggressive antifogging challenges but also enables quantitative analysis of the antifogging performance via real-time monitoring of transmission levels as well as image distortion is also described.

Abstract Image

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It reminds me of this that I saw at CES 2013:

22 thoughts on “Cooltech: a nanoscale foglifter and frost inhibitor coating

  1. What about Windshield Wipers? Will this lead to having to re-coat the windows every month? Will the anti-freezing nature of the coating hold to -40 (or below)?

  2. Mike – I think the best application for an anti fog coating would be on the inside of the windshield as there is no wear in the inside and fogging on the inside is common. Don’t see much use for exterior coating as you note, from experience wearing glasses these coatings all scratch very easily and would not be suitable for use in conjunction with windshield wipers and snow scrapers etc. Otherwise, look forward to seeing this on my next pair of glasses.

    Now if only they could come up with a new anti-bias and anti-marxist coating for the news media….


  3. I use the same material to coat fletching on arrows so when they do not get wet. It’sLike and Aerogel dust but will try it on my phone.

  4. We already have an excellent coating for the outside of windows – rain-x. I’ve been using it for over 20 years and often when it’s raining I don’t even need wipers. Ice and snow lifts off instead of scraping. Rain-x also has an interior anti-fog formula, but I found it completely useless in a winter climate – all it did was spread moisture across the entire interior, making a mess. Luckily it cleaned off ok.

    This stuff is great tech – glass is an ancient technology that can stand improvement. I’m still impressed with the “gorilla glass” on my phone, it resists scratches, oils and water quite well but as I understand it it would be far too expensive to scale up to car window size.

    Also there has been an incredible video distributed all over Facebook about a hydrophobic coating, demonstrating it on boots, gloves, cinder blocks, etc. Cool stuff!

  5. I’ve used Rain-X for about 30 years.
    Problem with this new coating that absorbs water molecules. Some alarmist will want to paint the whole world with it claiming it will help prevent heavier rains and deeper snow.

  6. Years ago there was a product like this for the internal parts of engines. It was called Slick 50 made by Petrolon in Colorado. It was a PTFE (polytetrafloroethylene) that coated the engine parts and reduced friction. Had the coefficient of friction like rubbing two melting ice cubes together. Worked. My engines ran cooler and I got better gas mileage. Petrolon was bought by Quaker State and Quaker State has ended making it as far as I know.

  7. CodeTech on February 27, 2013 at 12:41 pm says:
    ‘We already have an excellent coating for the outside of windows – rain-x. I’ve been using it for over 20 years and often when it’s raining I don’t even need wipers. Ice and snow lifts off instead of scraping. Rain-x also has an interior anti-fog formula, but I found it completely useless in a winter climate – all it did was spread moisture across the entire interior, making a mess. Luckily it cleaned off ok.’

    May I respectfully agree and disagree. Rain-X is, indeed, great stuff and neat to watch as it works. It doesn’t work with the mist trailing behind cars, however. But with normal rain drops and highway speeds it’s great. Trouble is that wipers will eventually wear it off so I reserve it for the side windows. For the windshield I use ‘PIAA silicon wipers’ (just Google it). These wipers come with a glass coating solution like Rain-X but the ingredient is also built into the wipers so as you use them it’s replenished on the windshield.

    I disagree about the Rain-X anti-fog. It’s the only anti-fog solution I’ve ever found that works good. In my experience it turns the mist on the windows into a thin, continuous sheet of water that one can easily see through. I definitely wouldn’t use it on the windshield though, just the side windows. The defroster’s a far better bet. And I wouldn’t recommend it for anyone who smokes. It’ll attract the smoke residue and make a mess.

    Best wishes. And safe motoring to all.

  8. A low-tech alternative to prevent windshield fogging is a cloth pouch of Bull Durham rolling tobacco. The pouch wipes away fog and leaves a film or residue that resists further fogging. I used that method in the olden days in vehicles with bad defrosters. The pouch has a drawstring that you can use to hang it from the rear view mirror. This alternative is also mentioned in:

    http://forum.studebakerdriversclub.com/showthread.php?68168-Best-anti-fog-solution

    “When I was a little kid I remember a lot old men had a pouch of Bull Durham (tobacco) in their car. It came in a cloth bag with a draw-string closure. Just wipe the windows without opening the bag. They swore that was the stuff for keeping the fog off.”

    http://bismarcktribune.com/news/local/classic-police-car-still-cruising/article_0487d37a-4f6a-5526-aaeb-b1d09f50a075.html

    “On the dash sits a bag of Bull Durham rolling tobacco, used for defrosting the windshield and, in a pinch, for stop-leak in the radiator.”

  9. Stuff might be great for swimming or skiing googles. I swim laps and have trouble with fogging googles after 1/4 mile. The anti-fogging stuff they sell doesn’t work very well.

    Rain-X is good on the outside windows–I agree. It is really neat to go 40mph and not use the wipers. Just watch the rain droplets roll off the winshield.

  10. Nice,,,,,, seems like you could make contact lenses out of this stuff and make a fortune….

    I must say I learn something interesting on this site every single day and just want to say thanks!

    Todays word was hydrophobic :-)

  11. I was thinking this could be really great for motorcycle helmet visors. Fogging on the inside can be a big problem in certain conditions, and very dangerous.

  12. mkelly says:
    February 27, 2013 at 1:07 pm

    “Years ago there was a product like this for the internal parts of engines. It was called Slick 50 made by Petrolon in Colorado. It was a PTFE ”

    TUFOIL TUFOIL TUFOIL! My Alumisil Block Audi A-8 is @280K miles, and I started using it at 120K. I had an V6 Acura with 250K (from 177k) No discernible internal engine wear. Made in New Joysey. Absolutely fantastic lubricant.

  13. I wonder how long it will take before the chemophobe community brews up a reason to have this stuff (or at least, one of its components) demonized like the harmless BPA plasticizers that keep plastic bottles from becoming brittle.

  14. With this stuff on my glasses I could read the menu when I enter a lunch joint in winter. I’m looking forward to that!

  15. CodeTech says:
    February 27, 2013 at 12:41 pm
    This stuff is great tech – glass is an ancient technology that can stand improvement. I’m still impressed with the “gorilla glass” on my phone, it resists scratches, oils and water quite well but as I understand it it would be far too expensive to scale up to car window size.

    ————————

    …Then you are going to really love transparent aluminum:

  16. The “dust” from polishing/buffing the car wax on your car does the same as rain-x.

    But wait, newer cars are clearcoated and few people that I know bother to wax their cars anymore. In the old days it was a necessity if you wanted your car to shine.

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