# Nanotube = "the strongest material that will ever be made"? **URL:** \ **Category:** Factual Questions\ **Created:** [July 16, 2002, 2:14pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234 "2002-07-16T14:14:56Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![jawdirk](https://avatars.discourse-cdn.com/v4/letter/j/df705f/32.png) [@jawdirk](https://boards.straightdope.com/u/jawdirk)\ **Post date:** [July 17, 2002, 5:46pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/21 "2002-07-17T17:46:34Z")
[nitpick] Nanotubes aren’t carbon-60. The molecules can have arbitrary numbers of carbon atoms. Also, there isn’t just one molecular structure for nanotubes. There are straight nanotubes and spiral nanotubes, for example. [/nitpick] ---
**Author:** ![sturmhauke](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@sturmhauke](https://boards.straightdope.com/u/sturmhauke)\ **Post date:** [July 17, 2002, 6:34pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/22 "2002-07-17T18:34:33Z")
> [@](#): > > \*Originally posted by bryanmcc \* > \*\* > The _only_ thing holding nanotubes together is the electromagnetic force. Carbon atoms themselves are basically a fluid - they won’t hold any form. My point is that in the environment in which these things are usually found – earthlike for nanotubes, neutron stars for neutronium – they _do_ have phenomenal strength. Try shooting a bullet through a neutron star and see how far that gets you. 🙂 > -b \*\* Carbon atoms are _not_ basically a fluid. They have a valence of 4, meaning they can chemically bond with up to 4 other atoms. Maybe you’re thinking of graphite. Graphite is a lubricant because the carbon bonds in sheetlike forms, with the sheets sliding over each other, not because each individual atom remains unbonded. As for your bullet, imagine a big sandbag. Instead of neutrons being held together by gravity, you have sand grains being held together by a sack. While the sandbag can stop a bullet, you wouldn’t want to build anything permanent out of it. Furthermore, if you take a handful of sand out of the sack the grains don’t stay together anymore. While you can put the handful in a smaller container, gravity doesn’t scale down in the same way. ---
**Author:** ![bryanmcc](https://avatars.discourse-cdn.com/v4/letter/b/eada6e/32.png) [@bryanmcc](https://boards.straightdope.com/u/bryanmcc)\ **Post date:** [July 17, 2002, 6:57pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/23 "2002-07-17T18:57:53Z")
> [@](#): > > _Originally posted by sturmhauke \* > \*\* > Carbon atoms are not basically a fluid. They have a valence of 4, meaning they can chemically bond with up to 4 other atoms. Maybe you’re thinking of graphite. Graphite is a lubricant because the carbon bonds in sheetlike forms, with the sheets sliding over each other, not because each individual atom remains unbonded._\* I was being a smartass. A hypothetical collection of single carbon atoms would indeed be a fluid – basically a bunch of little ball bearings. You’re not likely to get that (although I don’t think there’s any reason why you theoretically couldn’t), so let’s fill up the valences with hydrogens. What do you get? Methane. A fluid. My point was that the reason for the stability of the nanotubes is as arbitrary as the stability of the neutronium. Neutronium is incredibly strong under immense gravitational fields. Carbon is immensly strong when bound to for other carbons in the form of diamond. It is even stronger when arranged in forms like C60 or nanotubes. Neutronium is not stable when there isn’t an immense gravitational field around. Nanotubes also have conditions where they become unstable. I’m not an expert, but I suppose two of those would be extremely high heat, and intense gravity like on a neutron star. These conditions would result in the breakdown of the nanotube, just as neutronium breaks down in the absence of gravity. However, the discussion is on what is stronger, not what their various states are. Ice is relatively strong. Just because steam is an amorphous, thin substance does not rob ice of its strength. > [@](#): > > \*Originally posted by sturmhauke \* > \*\* > As for your bullet, imagine a big sandbag. Instead of neutrons being held together by gravity, you have sand grains being held together by a sack. While the sandbag can stop a bullet, you wouldn’t want to build anything permanent out of it. Furthermore, if you take a handful of sand out of the sack the grains don’t stay together anymore. While you can put the handful in a smaller container, gravity doesn’t scale down in the same way. \*\* Once again, I am not talking about building bricks out of neutronium and using those to make skyscrapers. I am saying that neutronium in its stable form (i.e., in a neutron star) is inherently strong. No you wouldn’t want to build anything out of it, but it is still strong. Hit a neutron star with a giant hammer made out of nanotubes, and the hammer will break before the neutron star. -b ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [July 17, 2002, 7:13pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/24 "2002-07-17T19:13:18Z")
> [@](#): > > \*Originally posted by bryanmcc \* > \*\* > The _only_ thing holding nanotubes together is the electromagnetic force. Carbon atoms themselves are basically a fluid - they won’t hold any form. My point is that in the environment in which these things are usually found – earthlike for nanotubes, neutron stars for neutronium – they _do_ have phenomenal strength. Try shooting a bullet through a neutron star and see how far that gets you. 🙂 > -b \*\* I think you’re missing the point here. Carbon atoms in nanotubes link together through the electromagnet interactions of their valence electrons. Because of these interactions, carbon atoms want to stick to each other. You have to pull them apart with some force to break the valence electron bonds. This is what makes nanotubes a solid (not a liquid), and gives them their high tensile strength. Neutronium is made up of neutrons jam-packed into a solid mass. With no electrons and no charge to them, there’s no electromagnetic interaction to hold them together. In fact, the neutrons in neutronium very much _don’t_ want to be held together - they’re actually pushing each other apart with a lot of force. It’s only the intense gravity in a neutron star that keeps the neutronium from violently disassociating into normal matter. Since there’s no attractive force (and in fact, a very high repulsive force) between the component neutrons in the neutronium, it has no tensile or shear strength. If you could somehow make a beam or rod out of neutronium, it would offer no resistance to being pulled or cut into two pieces. Neutronium has no intrinsic strength whatsoever. True, a bullet fired into a solid sphere of neutronium won’t get very far. That’s because neutronium is vastly more dense than the bullet. If you throw a wooden sphere at the ocean, it won’t penetrate far either, but it doesn’t mean that water is stronger than wood. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 17, 2002, 7:20pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/25 "2002-07-17T19:20:42Z")
Neutronium has phenomenal compressive strength, and is probably the strongest possible material in that regard. However, it has zero shear strenght, and even less tensile strength, which together make it absolutely useless for building anything other than neutron stars. Carbon nanotubes, meanwhile, have the strongest tensile strength of any known substance, a considerable shear strength (against the grain, at least), and a nonzero compressive strength, making them _very_ attractive as a structural material. Don’t get to excited about nanotech manufacturing, by the way. Most folks think of it as push a button, get a skyscraper, but it’s much more realistic to think of growing a tree. How long would it take to grow a two thousand foot tree? That’s about how long it would take for a two thousand foot skyscraper or ship. ---
**Author:** ![bryanmcc](https://avatars.discourse-cdn.com/v4/letter/b/eada6e/32.png) [@bryanmcc](https://boards.straightdope.com/u/bryanmcc)\ **Post date:** [July 17, 2002, 8:14pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/26 "2002-07-17T20:14:00Z")
> [@](#): > > _Originally posted by AndrewL \* > \*\* > Since there’s no attractive force (and in fact, a very high repulsive force) between the component neutrons in the neutronium…_\* What do you call gravity if not an attractive force? > [@](#): > > _Originally posted by AndrewL \* > \*\* > Carbon atoms in nanotubes link together through the electromagnet interactions of their valence electrons. Because of these interactions, carbon atoms want to stick to each other. You have to pull them apart with some force to break the valence electron bonds. This is what makes nanotubes a solid (not a liquid), and gives them their high tensile strength._\* [italization mine] Now you’re adding the word tensile. I will agree that neutronium has little, if any, tensile strength. The problem with this debate is that we’re using different definitions of the word “strength,” which makes it a pretty pointless argument. My whacking-with-the-hammer argument is about the compressive strength of neutronium, which is incredibly high. Insurmountably high, most likely. I’d be willing to wager, however, that the amount of compression force that neutronium can withstand is significantly higher than the amount of tensile, shear, compression, or any other type of force that nanotubes can withstand. But you sure as hell wouldn’t want to build a bridge out of it. -b ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [July 17, 2002, 8:17pm UTC](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234/27 "2002-07-17T20:17:05Z")
> [@](#): > > \*Originally posted by DMark \* > \*\*For example, I think shrink wrap is the most annoying material ever made, but I am sure it is only a matter of time before they make it out of clear sheets of nanotube - thus making it even more annoying and impenetrable to boot. \*\* Great, I suppose that means they’ll start wrapping CD’s in nanotube sheets then. 😃 [Previous page](https://boards.straightdope.com/t/nanotube-the-strongest-material-that-will-ever-be-made/119234.md?page=1)