Scientists Create Flubber-Like Effect Using Nanotubes

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Now I'm no scientician, but I can tell you that the following video shows some seriously weird science. Basically, researchers set up a "superhydrophobic carbon nanotube array" (where "array" I think effectively means "board"), then dropped water droplets on the surface, filming the results at very high speed (several thousand frames per second). Weird stuff happens. The droplets bounce, they hop, and they even merge into mega-droplets. It's strangely mesmerizing and nerdy.

The authors describe their video as follows:

Video from the paper "Bouncing Water Droplet on a Superhydrophobic Carbon Nanotube Array," authored by Adrianus I. Aria, Morteza Gharib, published online on ArXiv, Submitted on 7 Oct 2010: http://arxiv.org/abs/1010.1351

The first two parts of the video show the impact dynamic of 30 microliters water droplet at different impact velocity. At low impact velocity of 1.03 m/s, the water droplet deforms upon impact and eventually bounces off completely of the surface of the array. At higher impact velocity of 2.21 m/s, the droplet breaks up into many smaller droplets and eventually bounces off completely of the surface of the array.

The coefficient of restitution of water droplet at very low impact velocity can be seen clearly by dropping a water droplet on a slightly tilted carbon nanotube array. At tilt angle of 2.5 degrees the droplet skips off of the surface of the array multiple times without showing any sign of pinning on the surface of the array, as demonstrated in the third part of the video. The fourth part of the video shows the sliding/rolling behavior of the droplet along the surface of a U-shaped carbon nanotube array. The fifth part of the video shows the impact of two identical 14 microliters water droplets to one another on a U-shaped carbon nanotube arrays. Upon impact, these two water droplets, which come from the opposite direction, merge to form one larger droplet.

Note: the action doesn't start until about 20 seconds in, and there is no sound.

For similar stuff, check out this post from June: Crazy Video: Super-Hydrophobic Substances.

(Via Daring Fireball.)

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October 14, 2010 - 6:35am
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