Nanotube Update – buckytubes

In October of 2000, we spoke with nobel laureate Richard Smalley about his work on carbon nanotubes — also called buckytubes.

Model of a nanotube.

Scientists are creating materials that seem to be straight out of science fiction — hollow fibers only a billionth of a meter wide that are strong as steel, as light as aluminum and can conduct electricity.

These “carbon nanotubes” could lead to a wide range of advances — from faster computers to probes for identifying cancer cells. Richard Smalley is a professor of chemistry and physics at Rice University in Houston. He’s studying carbon nantotubes — but he says progress has been slow. He says one of the biggest challenges with his research is to get a large number of nanotubes, all at the same length. He’s trying to find a way to cut nanotubes down to specific lengths.

Richard Smalley: Imagine you sit there with a pair of scissors, why don’t you just do it that way? Well, these things are too tiny, and I need gazillions of little cut pieces and I need to do it efficiently. And it turns out that almost every, not all, but almost every one of our future projects requires that we solve that problem. And we’re gonna find it. I’m sure it’s out there, but we haven’t found it yet.

Smalley is looking for a chemical process that can do the job. When we spoke with him last in 2000, Rice University professor of chemistry and physics, Dr. Richard Smalley, told us about the incredible properties of carbon nanotubes. Nanotubes, or buckytubes, are super-strong molecules made of a single layer of carbon atoms rolled into a tube. Depending on their size and shape, these molecules only one-billionth of a meter wide can conduct electricity as well as copper can.

Buckytubes have incredible potential — they could replace silicon to make faster and smaller computers — they could be woven into super-strong materials and quantum electric lines — or even be injected into the human body as probes for cancer.

Some nanotubes can conduct electricity as well as copper can. They may be the only organic molecules that can conduct electricity. Organic molecules are rings or chains of carbon atoms that often have other atoms such as hydrogen, oxygen or nitrogen attached to them. They’re usually associated with living things. But in this case, these carbon nanotubes are manmade organic molecules.

According to Richard Smalley, “Well, this is the first organic molecule we ever found that conducts electricity … like a metal does. In fact, now that we understand why it does that and we look elsewhere in the periodic table, we’re probably also looking at the last organic molecule that can do this, this is really unique. And electricity is so important to modern technology … and on top of that, it is the strongest molecule you can make … That’s why I don’t worry about anything else but buckytubes. ”

Smalley’s lab is trying to figure out how to coax the tubes to break apart by themselves, using a series of chemical reagents to bind, cut and separate the tubes. He says “It can’t be done with tweezers or knives. It has to be done chemically. You have to be even sub-nano to do this. That’s down to the realm where there aren’t any fingers, there aren’t any knives that are sharp enough. The sharpest knife that you can make in the universe is a diamond knife, which is cleaved in a certain way so that the leading edge is just a single atom of carbon. But even that isn’t sharp enough or clean enough for us to do what we need. So it has to be chemistry that does the cutting.”

One of Smalley’s latest ideas is to replace copper electric lines with wires made of nanotubes. When electricity flows down a copper wire, the electrons inside move chaotically. But when electricity flows down a special kind of nanotube, the electrons inside move in a quantum way, almost as if they were directed, like bullets from a gun.

According to Richard Smalley, “Well, it’s really cool. A regular wire conducts electricity by electrons moving chaotically. In a sort of a random walk entering on one side they have to figure out a way to go to the other side and it’s chaotic. In a quantum wire, they behave as if, it’s as if though they know where they want to go. They can only go one direction, right down the wire. There is no ability to walk to the side, because in these tubes, there is no side. The electron takes up the whole tube. And it does this because of its quantum behavior it has a wave aspect to it.”

Because certain nanotubes, called the armchair tubes, conduct electricity in this quantum way, and because they’re much lighter than steel and aluminum, they could potentially be woven into thinner, stronger power lines to supply global power.

But right now, scientists only know how to make a mixture of nanotube types. In order to get an armchair tube, they have to painstakingly sort them from the mixture one by one. Until they can sort and produce the tubes more efficiently, scientists will have to put their loftier goals aside.

According to Richard Smalley, “In any event, these are all dreams for the future right now. We’re still dealing with these tubes where we don’t just have armchair tubes. We have a mixture of them, so we must learn to sort out just the armchair tubes, we need to learn to spin them in continuous fibers and actually measure these properties. We’re working on this now, maybe every idea I’ve got will be great, which never happens, but if it did, then maybe we could have our first quantum wires within a couple years.”

Nanotubes are relatively easy to make, in fact, ancestral humans may have unwittingly created them in campfire soot. Right now, at about $400 per gram, Smalley’s carbon nanotubes are more expensive than gold.

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