TechStuff Classic: TechStuff Plays with Carbon Nanotubes

title tech Stuff Plays with carbon Nanotubes. Yes, carbon nanotubes the stuff of the future that is persistently the stuff of the future and never seems to be the stuff of right now. I mean that's not entirely fair. We've done a lot of work in carbon nanotubes and there's been a lot of progress made, but it's been one of those futuristic things for a long time now. So let's listen back on two thousand thirteen Jonathan joined by

Lauren Vogelball as we talk about carbon nanotubes. First, we thought that we would talk a little bit about why carbon is cool, because um so so it's it's an element, incredibly uh popular element here on the planet Earth. It is way up there, it is. It is in fact, the fourth most abundant element in the universe by mass um after hydrogen, helium, and oxygen and the second most abundant element in the human body. Yeah yeah, we are

what is known as carbon based life forms. Yeah. Um. And all of this is made possible because carbon atoms are these nifty little hexagons made with six electrons um. They they bond very easily with one another. Actually, if they bond in a lattice structure, which is a hexagonal structure, do you have a sheet of that? So you've got a whole bunch of carbon atoms that are molecularly bonded to one another in this hexagon pattern. Here in the South.

I like to call it chicken wire. Anyone who anyone who lives in any story a rural environment who has seen chicken wire, that's kind of what a sheet of these carbon atoms and molecular structure look like. We call that sheet graphing. So let's say say you've got this sheet of graphing, which is essentially two dimensional, right, because adams don't really have a lot of thickness to them, so they are you're you're talking about with and length,

you're not talking about depth. And I mean that's you know, one atom thick that's thin enough to call it two dimensional. Absolutely. So you've got the sheet of graphing. Let's say, then you roll the graphing into a I don't know, burrito like structure. It's not necessarily going to be filled with cheesy beany goodness. You know, I kind of want a carbon nano to burrito now. I am craving burritos like you wouldn't believe. But but no, No, that's what we

call a carbon nanotube. You take that sheet of graphing, this this hexagonal molecular structure of carbon, and this is just carbon you and you roll it up and that's carbon nanotube. But you know, carbon is kind of an amazing thing anyway, because carbon can take on so many different forms, right right, Yeah, I mean it's what diamonds and graphite are both made of, and it's totally different a little little bit. I mean, you know that's you've got.

You've got the hardest substance, the hearts, natural substance known on Earth, right, and then you've got what you put in pencils. Essential So yeah, something soft enough that paper is paper, paper is its match, right right? Yeah? Yeah, So so this is something that we call allotropes. Now, an allotrope you know, you're like, what the heck is that? Well,

if you if you've studied chemistry, you know. So I apologize to all the chemists out there who are screaming at me because I'm assuming they don't know what an allotrop It's okay, I know. You know. Also, y'all can go just get a soda for the next about So, an allotrope is any of two or more physical forms in which an element can exist. So you we have these elements that can exist in different physical forms, and carbon is a perfect example. Lauren was just pointing out

diamond versus versus a graph fite. So you've got these two very different kinds of forms, but they're still the same basic element. Uh well, carbon nanotubes are very similar in that way. We'll talk a bit more about the different properties that carbon nano tubes can have and why they can have different properties, but we need to lead up to that. Yeah, yeah, yeah, Well this entire carbon nanotube business was discovered in by Sumio Ijima, I believe

is the way that you pronounce it. Um apologies to my Japanese teacher. Um. Although research into into creating these sheets of graphine stretches back into the nineteen fifties. Um, and all of these are there. They're actually two processes for making them. One of them I'm not extremely familiar with, and it's written all the way down at the bottom of my notes, so we're going to cover that one later.

That's a wet application, the general way of making carbon nano tubes as a RYE application, and you thermally strip carbon atoms off of carbon bearing compounds. Wow, that sounds complicated, or at least violent and violent. Violent at an atomic level,

that is extremely violent. Yeah, and so this is well, this is what produces these these extremely these atom thin sheets UM that that you then roll into a tiny tiny tube and by tiny tiny, I mean about a nanometer or two in diameter UM and just you know, just to just to recover this nanimeter is one millionth of a millimeter, so it's one billionth of a meter, So it's small, right, And then you at least for the longest time, Uh, these these carbon nanotubes could be

at most about a millimeter long. Now that's changed recently, right, right, But I mean even a millimeter long is pretty impressive because that's that's a million times as long as it is. Why that's I mean, that aspect ratio is incredible. I mean, it's one of the things that really made carbon nanotubes a fascinating thing to look at, because you're thinking, if you're looking at the dimensions, by one dimension, this is incredibly tiny, and by the other, in comparison, it is ginormous.

I mean, think about the technical term. Think if you saw a bus that was a million times longer than it was wide or or or long cat. If long CAT were so long that it were a million times longer. Thank you, Thank you Lauren for bringing it directly into an analogy that is relatable to everybody. I was going with the bus, What was I thinking? I was mostly thinking I would not want to be behind that bus.

I bet they would make really wide right turns. Like we're on we're on the internet, Okay, we if we don't incorporate cats into the conversation, we're going to be fired, right, We're lost. But anyway, Yes, this is one of those amazing properties of of carbon ano tubes. The other thing that I find really interesting is that carbon ano tubes will have very different properties depending up on how they are rolled. Because it's mostly the direction of the role.

So it really is the how that those hexagons I was talking about in the graphing, how they are aligned in comparison to the actual role of this sheet. Uh. And depending on how you do it, it can behave like uh, like a metal, so a conductor, so it will conduct electricity. But if you roll it a different way,

like at a slightly different angle. And if you guys are having trouble visualizing this, just take a sheet of paper and roll it along the short side, or roll it along the long side, or roll it along the diagonal. These are all the different kinds of ways you can roll sheets of graphing and you get different properties. So you roll it one way, it acts metallic like a conductor,

so it's conducting electricity. You roll it another way it acts like a semiconductor, which means that in some situations it does conduct electricity and in other situations it acts as an insulator. This gives it an incredible flexibility as far as applications are concerned. You can use it in all sorts of electronic applications, which we will get to

a little bit when. Yeah, and it also depends on what kind of you can roll them into all kinds of different interesting shapes using using an atomic force microscopes also called scanning force microscopes, which are which are things that have these these tiny bitty little nanimeter probes on the end of them, and you can use them to basically poke around a nanotube until it's the right shape, the right shape for your process. This is pretty amazing.

I mean, we're talking about manipulating things that are just slightly larger than the atomic scale, right, I mean, it's something that's really difficult to to visualize. Now, there there are some neat ways of kind of getting an idea of how precise we can be these days. My favorite, we've talked about it on the Tech Stuff podcast in the past. My favorite illustration is that ibm UH several years ago used a similar type of microscope to manipulate individual atoms to spell out I B M on a

silicon wafer. That is delightful. Yeah, so you're talking about being able to when when we're able to manipulate individual atoms, then obviously this is we've got this level of precision that to me is mind boggling. I mean, it's really exciting. But some of the other properties of carbon nanotubes is again depending upon the way you you you roll these tubes, it can be an incredibly strong material, stronger and lighter

than say, steal, hundreds of times stronger than steel. Yeah, according to to to some Well, you know, here's the thing. There's a theoretical limit to the tensile strength of carbon nanotubes, and then there's the limit that we've actually seen. Right, and as we get better about creating nanotubes than those

two numbers get closer together. But in general, in the experimental phase you might not see as incredible a display of strength as you would aspect when you start running the numbers via you know, mathe But for an example, you could take a a cable that if you were to cut the cable and look at and measure the diameter you're talking about like a a one millimeter diameter of this cable, nanotube of that size could hold approximately

six thousand fo or fourteen thousand pounds. And that's and and and a millimeter, I mean, that's that's what like like about the width of a human hair. Well, a millimeter would be one millionth of a nano, one million times the size of a nanometer. That really brings it into perspective one million that I ruined my own joke. To be fair, I'm not working on very much sleep, right, I think I think a millimeter is about it's about

the size of a head of a pin. Actually, the hair a human hair is like a few hundred thousand nanometers, depending upon the person's hair, because human hair comes in a but but yes, I mean, the point being that you're talking about an incredibly thin cable that could hold an amazing amount of weight considering the dimensions of the cable. Now, granted again, this is theoretical, you know, when we talk about real carbon nanotubes and the real experiences we've had,

it's a little bit different from that. But the potential there is to build certain types of materials, certain types of products using this stuff that can have fantastic properties. And just to be clear, we're saying stronger than steel. That's really mostly tension strength when you're talking about um other types of impact. Because carbon nanotubes are hollow, they

can buckle. So let's say that you have just somehow you have managed to make one carbon nanotube that's you know, Lauren Height, and then you have a force impacting that along the side of the carbon nanotube, so it's not pulling on the nanotube, it's pushing against the side right into the chewy center. Right. Well, that chewy center might just buckle and the carbon nanotube bends and you think, well, that was But it's the same sort of thing like

saying the strength of a rope. The strength of the rope is how much weight it can pull, not pushing against the rope in the middle of the middle of the rope. It doesn't make any sense. And let's be pulped taught, And that's a whole different version of physics that we would need to get into right right exactly. But but that's one of the other things to to keep in mind is that even though it is an incredibly strong material and theoretically one of the strongest materials

we've encountered, uh, that's only in specific use cases. It's not like you would build a carbon nanotube wall and it would be immune to everything else known to man, right, although I'm sure there are ways you could do that, like maybe with some sort of woven fabric made out of carbon nanotubes, but an individual carbonanitude it's not the case. Let's take a moment to thank our sponsor, and now

we'll return to our regularly scheduled tech stuff podcast. Alright, so, um, so there are there are many many applications that these nanotubes can be used for. Like, like we mentioned before, their engineers are looking at incorporating them into building materials, perhaps for vehicles. I mean, imagine if you had a vehicle that was six times lighter than than the cars

that are running around today, right that and that. If you're wondering why you would want a light car, one reason is that it means that you don't have to use as much fuel to push that car around. A lighter car means less work for the engine to do. If if the engine has to do less work, it theoretically needs less fuel. So we could end up with cars that are still gas powered but end up requiring

far less fuel have greater efficiency. Or we could of course use it in other like hybrid cars and you know you're again you're placing or even electric vehicles or something like this airplane or yeah, yeah, there's some great airplanes would be fantastic because, as anyone has pointed out, if you're talking about someone who's who's green conscious and they're trying very hard to live a green friendly life style.

They basically need to avoid airplanes entirely. One flight on a plane and you have just like you know, you're essentially erasing any good you're doing with your entire green life at home. And that's that's just a hard reality of what it takes to move. Yeah, so that's a great example. You actually pointed out something else. A future use of this technology could be something that we did an episode of tech Stuff about a few years ago.

Space elevators. Space elevators. Yeah, these are these are really nifty things. If you guys have not heard of this, um, you you should have by now, you're a bad tech stuff listener. But that's okay, because you can fix that. I still love you, Yes, yes, no, No, I just I had to. I had to moderated of Facebook thread the other day. I am being the social media here. It has stuff works. I'm if people are are being jerks on Facebook, they I'm the one who has to

clean it up. So don't be jerks on Facebook, y'all. Um. It's a very special episode of tech Stuff, But no elevator, space space elevator. No, well, I mean, okay, the point of my story here, I've start started to stutter. Excellent. Um, the point of my of my story was that you shouldn't be a jerk on Facebook. Now, No, I had a point. My point, well, let me let me let me at least explain what space elevator is. How about that? Because I'm dying here, I can I can at least

give it a shot. So let's say. Let's let's say you put an object into orbit, stationary orbit around the Earth. Okay, so it has to be uh, it's the object is sort of a counterweight, essentially, So you've got a counterweight orbiting the Earth, and the thing connecting the counterweight to Earth is a very strong cable, and you use the elevator,

which is essentially attached to the cable, to transport in anything. Really, it could be people, although cargo would be a lot easier than people, because with people you gotta worry about, I don't know, keeping them alive and stuff, moving them to Yeah, I guess if we're moving dead people, it's okay. So if we want to have a space cemetery out there, I wouldn't mind that, except that I actually plan on donating my body to science fiction. Uh so the the Yeah,

you have an elevator that has this counterweight out there. Okay, you're just pick up that. Now I'm with you. I'm with you, and keep going so the elevator can travel up the cable. The the nice thing about this is the based on this design, you might be using things like lasers to actually power this elevator. Uh. The elevator wouldn't have things on it like thrusters, like rocket thrusters, the way we would with a a traditional rocket ship

to get stuff into space. It would mean that it would take uh less energy in theory to deliver payloads to utter space. You wouldn't have to worry about problems like uh catastrophic failure when you're talking about propellants that can be incredibly dangerous under the wrong conditions. And also, I mean, just like we were saying, if you if you take one airline flight, you're basically erasing the entire good that you've done on your carbon footprint all year.

You know, the cost of launch in terms of fuel and and just people and manpower is is ten thousand dollars per pound. That's per kilogram that's a bunch. So you've got you've got this need to find a cheaper way to get stuff into utter space if in fact we want to do that thing that which we do, I mean I do, yeah, because there's lots of fascinating stuff out there. So space elevators are a good way

of doing that. But one of the problems is that how do you create a cable that's going to be strong enough and small enough to make this a reality? And carbonano tubes might very well be the way that we solve that problem. Now, for a long time everyone said, okay, well here's the barrier, the barriers that we've got. We've

got this exactly. Yeah, yeah, we can make carbonano tubes, but there are a millimeter long at most, and so we don't have to make a whole bunch of them and tie the ends together teeny little bows in order to make a big, long one for the cable, but relatively ineffective. Yeah, so we'll get into some some new forms of manufacturer that have made that less of a problem. But even now we're still talking about this is science fiction as far as we're concerned. It's it's feasible, but

not possible. Given our technology right now, right now, But there are other applications that we could use carbonanotubes and including things like, uh like conductive plastics, So we can make electronics out of plastic materials and run carbonano tubes through the plastic, creating them a conductive layer, so that you can actually make products even small more than they are today. So instead of having a casing that is covering up the electronics, the casing would be part of

the electronics. You could have you know, a credit card, thin smartphone. Yeah, yeah, that would that would turn More's law right on its point he had. Yeah, yeah, there's some pretty neat stuff that could potentially happen. We also could have things like smart fabrics, so clothing that could have carbon nanotubes in it that might do things like monitor conditions like it could it could end up powering

various sensors. This would obviously be very important in uniforms like space suits or first responders outfits for things like firefighters, things like that, you know, things that that could benefit from this. But even from a more consumer standpoint, we could even have I don't know, like clothing that tells you how active you are and whether or not you're getting enough exercise and don't even have to put on a speedometer a little Nike fit wristband, right, you'd be fine.

You just you know, you put on your clothing, and that tells you or may say things like, for Heaven's sake, wash me. You know that that goes out to everyone I went to college with. There other clothing applications. I mean, maybe not so much for daily use, but but carbon antotubes could be used to create some really terrific body armor.

Oh yeah, sure, yeah. Again, we're talking about the incredible strength, and if it's woven the right way, you're talking about something that could have a great applications for anyone who might be in military or law enforcement to provide a level of protection that is really unheard of at this point. I mean, we've got some great technology out there to keep people protected, but this would be a step of

a huge step above that. Hey guys, twenty nineteen, Johnathan again, you know the one you hate, because it's time for us to take another quick break. Part of the problem here is that we're talking about a material that's still a little challenging to manufacture, especially in mass quantities. But there have been improvements in carbon nanotube manufacturing processes very recently. Yeah, actually, I'm we were, we were, and you know, we're recording

this in early January, UM two thousand and thirteen. And actually just today the Internet told me that, um that Rice University has announced a macroscopic hundreds of meters long mass producible carnin carbon nanotube thread. Yeah, this is this is incredible news because again, before we were talking about nanotubes that were a millimeter long, and that was considered huge. Now we're talking hundreds of meters. That is such an

enormous leap that it it boggles my mind. And it's all through this this wet method that they used to manufacture carbon nanotubes. Yeah, wet spinning method in which, um, and I'm sorry, I'm going to read this directly from my notes, which is probably a terrible thing to do, but in which clumps of nanotubes are dissolved in a bath of some acid stuff squirted through small holes to create long strands, and then the strands are wound into a big spool until they dry out. That's pretty incredible.

So really, the way I understand that is that we have dissolved the carbon nanotubes until they're essentially a liquid. You put them into what is essentially a nozzle, you squirted out in what is essentially like a giant icing thing where your favorite kind of cake, and you get this long string of carbon nanotube. That's exactly the way you wanted to be until you get that, you spoil it up and there you got You got a hundreds, hundreds of meters long carbon nanotube. Yeah, it's it's the

thickness of a human hair. Um uh And and not like I was saying earlier that you know, that's that's big. That's a bunch of a bunch of h space things measurements of stuff. It's much much larger than say, you know, a single carbon nanotube would normally be you know again one billionth of a of a meter in die ameter.

It's larger than that. Yes, And there there's a video and on the Internet of an LED lamp being both suspended and powered by this thread, right, so so that it's this tiny like human hair with cord that's holding a lightbulb, and the light bulb is lit because power is going going through and and it's it's completely suspended that way. So you think about that and you're like, all right, so we've got this very thin, very strong

stuff that can provide power across it. This could revolutionize electronics. Oh absolutely. And there's also there's also been a bunch of research into health applications for this. UM. It can be used as a delivery system for drugs and vitamins because carbon antitudes are are so bitty that they can they can really get in there, you know, they you can you can attach you can attach stuff to them and send them in through things and and be really

effective as an antioxidant. UM they naturally pick up free radicals in UH in blood systems. I used to do

that in college. Oh my, um you can. One of one of the really cool bits of research that I saw had people UM sticking an antibody onto the end of a nanotube UM and then letting a blood sample pass through it, and different kinds of tumor cells or viruses will get trapped by that antibody and then UM, so you can you can test for all kinds of things without having to do any expensive lab work in

the field in a couple hours. Interesting. Of course, this also leads to a dark discussion in that carbon nanotubes may also be depending upon their their structure, may be extremely hazardous to our health. And uh, there are a couple of reasons for this. One is that when you're talking about things that are on the nano scale, their properties change fairly dramatically. You can have materials that act as conductors in the macro scale, but on the nano

scale they might be insulators. You also may have things that on the macro scale are perfectly safe, but on the nanoscale are toxic. And one of the things that concerned people fairly early on in the research of carbon nanotubes, and has been studied extensively since then, is that carbon nanotubes, depending again on the specific structure that you've designed for them,

bear a striking resemblance to this substance called asbestos. And and for for for those young uns out there, this was an asbestos is a substance that used to be used in a lot of insulation. Um. Yes, it's fire retardant. Fire retardant, which which is great. I mean that's less fire good. Yes, yes, fire fire bad. As Frankenstein's Monster

taught us. However, Um, you know it was made up of these of these small, pointy particles that people would aspirate and it would get stuck in the linings of your lungs and your other internal organs and cause cause

lesions and metalalithiomia. No, that was not the word mesol. Yes, yes, the form of cancer that the lining around your organs, that's specifically what what we're talking about here, but but more specifically the lungs because you would breathe in these particles, and they're small enough so that they can, uh, they can infect a cell. Essentially, they can, uh, they can penetrate a cell. That's the best word for it, penetrate

a cell. But they are large enough so that the body's immune system cannot easily get rid of them, which is why it becomes a very dangerous substance. And the carbonanotubes bear some physical resemblance to those needle pointing fibers. Now, according to at least some research, I was reading one report that was kind of interesting, and I cannot pretend that I follow it completely because my my medical knowledge is uh, plucky and adventury. No wait, I'm sorry, that's

my military knowledge. Um by the very model of a modern tech stuff. Podcaster they it was from an online library, is actually from the Cancer and Aging Handbook. And the study suggested that carbon nanotubes could penetrate cells, but they did so in a different way than asbestos particles did, Like they both could penetrate cells, and they both could

cause similar outcomes. So, in other words, there is some evidence that carbon nanotubes could in fact be carcinogenic, but they do it in a different mechanism, Like there's a different mechanism for how they are they get enveloped by other cells or by cells, I should say not other cells, but by cells. And so the research actually suggests that there might be ways of creating carbon anotubes where they do not behave in this way where they are causing cancer.

They just kind of hang out, right, And that's one of the other problems about carbonano tubes is they have this bio persistence, meaning that if they are in a biological entity, they do not tend to break down right there. They're so strong and sturdy. Yeah, they don't react. They're nonreactive when it comes to that too, So you don't have it just you know, decompose into some other material or get absorbed and then you know, they're harmless, that's

the problem. They don't do that. So, but there might be ways of engineering carbon nanotubes so that they are not hazardous, right. And also all research I've read has suggested that it's not that we shouldn't go into making carbon nanotubes. Yeah, yeah, yeah, it's it's most people are saying that, yes, it's a danger, but these things are so useful that we we almost can't afford to to not continue researching them. And that most most of the most of the danger comes to people who are going

to be working in development development labs creating them. Um And that there are definitely lots of different air filters and other precautions that could be used to to lessen the danger to these important workers. Um And And that ultimately we may find ways of creating these as you know, so safely that it becomes a non issue. Um. Not

that you know, we can ignore it. That's the important part is don't ignore the fact that there's a danger, but but understand that there may be ways of working around that so that we minimize the danger to ourselves while maximizing the benefit that these things could provide us. So, yeah, I mean, it's it's you know, one of the things that definitely we have to keep in mind about technology.

I mean, just like your computer at home, assuming you have one, has some material in it that can be extremely toxic if you are if you're exposed to it directly. But computers are incredible benefit too. It's just that it's under specific circumstances that you can become very dangerous. Like let's say you catch it, it catches on fire, that kind of thing, or you're taking it apart to try and harvest the various uh metals and minerals that are inside your computer. That would be a bad thing to do.

Don't do that. So yeah, I mean it's just one of those things where you've got to keep in mind the various scenarios and uh and and remember to to treat it carefully. So guys, if you're out there playing with carbonano tubes, just you know, be careful. Yeah, you know, what you do in your spare time. Leave it to the professionals. Probably, I think it's it's probably the important important thing there. But I find this this whole area

of study very interesting. I mean, it does have the the potential to completely revolutionize everything that has to do with electronics. I mean you sit there and you think about how incredible things are right now, go and go to like see yes one year and take a look at a TV, and you see how thin they've become. Well, with this sort of technology, they could be even even, you know, so thin that when you mounted against a wall, you wouldn't be able to see the difference between the

wall and the TV. I mean, that's that's how thin we're talking basically basically a sticker. Just yeah, think. I mean, it's gonna take a while before we ever get there, so we can at least get to a point where it's gonna look like a piece of paper. And that wraps up another classic episode of tech Stuff. Hope you guys enjoyed it, and I look forward to revisiting carbon nanotubes. I think it's about time I do an update on that particular topic, because I guarantee a lot has happened

since two thousand. But if you guys have suggestions for future topics of tech stuff beyond carbon nanotubes, let me know. Send me an email the addresses tech stuff at how stuff works dot com, or drop me a line on Facebook or Twitter handle his text stuff h s W. I look forward to hearing from you, and don't forget to visit our website that's text stuff podcast dot com.

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