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Growing Nanotube Forests

4 minutes

(man) Imagine a material that would let you use your phone for weeks without a charge or would let you build an elevator to space! These elevators and batteries can one day exist using carbon nanotubes. Carbon nanotubes are tiny. Take this human hair, for example. You'd need 10,000 carbon nanotubes to make a rope as big as this hair. Despite being small, they're strong. This cotton string holds this Lego car. But this string made from carbon nanotubes could hold a real car. Carbon nanotubes are being used around the world. Take this badminton racquet. The frame incorporates carbon nanotubes, making it both lightweight and rigid, giving me a competitive edge.

(male) Too bad you still suck. Carbon nanotubes are super strong and conduct heat and electricity better than the wires in your electronics. With carbon nanotubes, you could make a phone that goes for weeks without charging. Why does my phone die, and where's my elevator to space? The truth is, carbon nanotubes are difficult to make. But I can show you how to grow them like grass. Like grass, the first thing we do is plant the seeds. This piece of tungsten foil will be our soil. I'll place it into this machine, which is called a sputterer. The sputterer applies a massive voltage to this piece of iron. When this happens, atoms are ripped from the iron's surface and deposited onto our tungsten foil, planting the seeds for our carbon nanotubes. Now our tungsten foil is planted with tiny iron seeds invisible to the naked eye. Let's grow nanotubes on them. Before we grow carbon nanotubes, what are they made of? On this carbon nanotube model, each white ball represents a carbon atom blown up a hundred billion times larger than the actual thing. Where do we get all this carbon? It starts in this tank of acetylene, a carbon-rich gas. Once I open it up, it will start flowing through these tubes and continues on... through this pipe, where it will eventually end up in this growth chamber. We've placed a small sample of our iron-seeded tungsten foil onto a heater, which I'll turn on now. When the iron heats up, it will melt into tiny droplets. When the acetylene touches the hot iron droplets, the carbon is absorbed, and carbon nanotubes grow like blades of grass. This is what they look like under a high-power microscope. As you've seen, making carbon nanotubes doesn't require some magical process, and they're already used in everyday objects. With more research, perhaps we'll get our space elevators. Until then, I'll just practice my game. Accessibility provided by the U.S. Department of Education.

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What if scientists could grow elevators to space? Or make phones that last for weeks without a charge? These things could be possible someday with an amazing material like carbon nanotubes. A MIT scientist discusses the curious way researchers create this super-material. Part of the "Science Out Loud" series.

Media Details

Runtime: 4 minutes

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Episode 1
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Grade Level: 9 - 12
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Episode 2
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Episode 3
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