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Nanostructured materials to put an end to icy airplanes and roads

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November 15, 2010

Icing on surfaces such as airplane fuselages could become a thing of the past, thanks to n...

Icing on surfaces such as airplane fuselages could become a thing of the past, thanks to newly-developed nanostructured materials

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Much to the chagrin of those of us in the Northern Hemisphere, winter is once again on its way. For many of us, this means a return to icy roads, sidewalks, power lines and even airplane wings. Traditionally, the main methods of getting rid of this ice – or at least, keeping it under control – involve the use of salt and/or de-icing chemicals. Both of these are labor-intensive, environmentally-unfriendly, plus the salt kills grass and causes cars to rust. Now, however, researchers from Harvard University are developing nanostructured materials that could keep ice from ever forming on surfaces in the first place.

Like the superhydrophobic coating developed by a University of Pittsburgh-led team that mimics the rutted surface of lotus leaves to reduce the surface area to which water can adhere, the Harvard team got their inspiration from natural models. Although the principle is the same, instead of the lotus leaf the Harvard team turned to the eyes of mosquitoes and the legs of water striders for their inspiration. In both cases, the insects are able to keep these body parts dry due to an array of tiny bristles that repel droplets of water by minimizing the available surface area.

The researchers proceeded to create silicon surfaces incorporating various nanoscale shapes, patterns and geometries, such as bristles, blades, honeycombs and bricks. When they watched slow-motion videos of supercooled droplets hitting some of these surfaces, they saw that that the droplets would initially spread out, but then retract back into a sphere and bounce off before they could freeze. The surfaces with interconnected patterns were particularly effective. On regular smooth surfaces, by contrast, the droplets would simply spread out and freeze.

Ice formation on aluminum (A), smooth silicon (B) and nanostructured silicon (C)

The nanostructured materials were shown to prevent the formation of ice down to a temperature of -30C (-22F). Even below that, what ice did form wasn’t able to adhere well, so would be relatively easy to remove.

“We see this approach as a radical and much needed shift in anti-ice technologies,” said team leader Prof. Joanna Aizenberg. “The concept of friction-free surfaces that deflect supercooled water droplets before ice nucleation can even occur is more than just a theory or a proof-of-principle experiments. We have begun to test this promising technology in real-world settings to provide a comprehensive framework for optimizing these robust ice-free surfaces for a wide range of applications, each of which may have a specific set of performance requirements.”

The research was recently published in the journal ACS Nano.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
5 Comments

I hope this works as hyped. There is a huge difference between "in the lab" and "in practice". I still remember when asbestos was the miracle material that could be used almost anywhere from floor tiles and fabric filler to heatproof gloves. Hopefully, nanoparticles won't simply become the next dangerous nanopollutants.

Bob
16th November, 2010 @ 07:30 am PST

If this can be applied to windows as well, cars would benefit from this, too, I suppose. Imagine, no longer needing windshield wipers in the rain, nor scraping off ice in winter.

BoilingOil
16th November, 2010 @ 07:36 am PST

Very promising - exactly as article suggests, if supercooled droplets can't freeze to the stuff on impact, then this needs to be on the leading edge of every aircraft wing and engine inlet, this will save lives.

PeetEngineer
16th November, 2010 @ 08:12 am PST

Can someone help me here. I'm trying to vizualize, on a highway, if the droplets spread out, then form a sphere, then bounce off, where do they bounce to? If this a stationary horizontal surface, say an eight lane freeway, what becomes of all these bouncing droplets. Be gentle please.! I'm not much on physics, chemistry or any of the sciences but I am interested.

Roselense
16th November, 2010 @ 10:43 am PST

Hold it. This works by reducing friction, so that ice doesn't stick to a surface. So, dry pavement would have about as much grip as an icy one, all year round.

Still very good for surfaces on pretty much any moving vehicle.

sstvp
17th November, 2010 @ 08:37 am PST
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