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Water inside carbon nanotubes turns solid at boiling temperatures, MIT researchers discover

By Shawn Knight ยท 13 replies
Dec 3, 2016
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  1. It’s common knowledge that water freezes at zero degrees Celsius (32 degrees Fahrenheit) and boils at 100 degrees Celsius (212 degrees Fahrenheit) in normal conditions. When confined within a carbon nanotube, however, all bets are off.

    While conducting an experiment that involved trying to send electric currents through water inside of carbon nanotubes, a team of chemical engineers led by Professor Michael Strano at the Massachusetts Institute of Technology (MIT) noticed some unexpected behavior.

    It’s been known for a while now that when water is confined in very small spaces, its freezing and boiling points can drop by as much as 10 degrees Celsius. What the team at MIT observed, however, was quite the opposite.

    Inside tiny carbon nanotubes, they witnessed water solidifying at a minimum temperature of 105 degrees Celsius – well above its normal boiling point.

    The diameter of the nanotubes played a significant role in the water’s behavior. The difference between tubes measuring 1.05 nanometers and 1.06 nanometers across changed the freezing temperature by tens of degrees.

    Equally as puzzling is the fact that water could even enter nanotubes at all as they’ve long been thought to be hydrophobic.

    More research will be needed but Strano thinks the discovery could lead to the creation of “ice wires,” or efficient highways to transport protons as water is around 10 times better at conducting protons compared to standard conductive material.

    Permalink to story.

  2. Uncle Al

    Uncle Al TS Evangelist Posts: 4,400   +2,858

    Hmmmmm .... wonder how this might be applied for use by my x-wife. Poor girl never could cook, just burned the water!
    lazer, davislane1, trgz and 1 other person like this.
  3. RzmmDX

    RzmmDX TS Guru Posts: 313   +67

    I wonder if this could be modified to act as a heat sink.
  4. namesrejected

    namesrejected TS Guru Posts: 398   +301

    Cool! Proton guns just around the corner!
  5. cuerdc

    cuerdc TS Booster Posts: 165   +39

    Interesting stuff, water.
    Greg S likes this.
  6. captaincranky

    captaincranky TechSpot Addict Posts: 13,917   +3,293

    But face it, she gave you the complete and utter smug satisfaction of saying, "burnt water for dinner again tonight, hon"? That had to be worth something. No? :confused:
  7. Yynxs

    Yynxs TS Addict Posts: 201   +78

    My immediate thought was, if this occurs with water..what other changes could occur? Relooking at cold fusion where speculation was the molecular space might have allowed nuclear interaction. Other speculation whenever I find that roll of Reynolds.
  8. treetops

    treetops TS Evangelist Posts: 2,253   +351

    uh its still boiling so its not any colder
  9. captaincranky

    captaincranky TechSpot Addict Posts: 13,917   +3,293

    Yeah but it would still be cooler than no heat sink at all... :D (OK, you caught me. I'm being really, really sarcastic here)...:rolleyes:

    Unless of course, were you to turn the computer off, and leave the heat sink on. In which case it would act as a heater, allowing faster starts from your computer, after leaving it out all night in the driveway, in extremely cold weather...(y)
    Last edited: Dec 4, 2016
  10. captaincranky

    captaincranky TechSpot Addict Posts: 13,917   +3,293

    Well, I think "freezes" might be misapplied terminology.

    I'm going to take a wild, uneducated guess here, and postulate the water isn't "frozen" per se. Given the 3 elements in the mix, carbon, hydrogen, & oxygen, the scale at which this is happening, and the amount of molecular activity brought on by applied heat, the water is likely "mimicking" or "masquerading" as, a carbohydrate.
    Last edited: Dec 4, 2016
  11. Skypickle

    Skypickle TS Rookie

    The diameter of the nanotube is only 5 water molecules across. But these researchers https://www.mpg.de/6362003/water-ice-crystal
    Say that you need at least 275 molecules to form an ice crystal. So the 'solid' phase of water cannot occur in the confined space of a nanotube. Rather a different 'boundary ' phase of carbon-water forms
  12. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 1,029   +546

    It is probably the hydrophobic nature of the CNTs that forces the solidification. As you increase the energy of the particles, they find themselves bound inside of the CNT and unable to leave. This would likely significantly increase the number of collisions between H2O molecules, giving the appearance of being a solid, without needing as many molecules as is normally required to form an Ice crystal as Skypickle points out.

    Still, I wonder why they were putting water inside of CNTs in the first place. The common conception is they are hydrophobic, plus CNTs already display ballistic conductance of both electrical and thermal energy. I find it hard to believe that anyone would go 'yeah, lets add thermally *capacitive* material (water) to increase thermal *conductivity.*' I think they were trying for something else entirely, which they aren't ready to publically talk about yet. My guess would a new kind of thermal heat sink, with both high conductivity from the CNTs and high capacitance from the H2O - and this would explain why they brought it up to such high temperatures in the first place, since CNTs don't heat up readily when an electric current is applied.
    Phr3d likes this.
  13. wiyosaya

    wiyosaya TS Evangelist Posts: 3,058   +1,536

    My thoughts are that the size of the nanotube is somehow forcing the molecules of water to align in a fashion where they do not move - thus giving the appearance of a crystallized set of molecules.
  14. Yynxs

    Yynxs TS Addict Posts: 201   +78

    Somewhere in non-available memory was some reading on crystal forming temperatures of water with additives such as salt and something to do with 'absolutely pure' water having different bonding reactions than just distilled water. I'm wondering if the size of the nanotubes creates an 'absolutely pure' water condition and whether that affects 'hydrophobic' as used to describe the carbon molecules. I know when I don't know so I'm sending this article to a friend 'Saint Jack' to see if he knows anything.

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