Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.
Oh, ice. That wonderful material that we have such a deep appreciation for. Yet I may just extend that love a little deeper. Let’s take a look at some surprising science behind ice that only increases its versatility and its wonder.
How could such a thing as ice on fire even be possible? Enter the wonderful world of hydrates, or ice structures that trap elements. They usually create a cage-like structure with the trapped material in the center. If you happen to get methane inside we have methane hydrates, and as anyone with methane experience will tell you it’s flammable. On top of this, the methane is trapped under pressure conditions, so when you have the hydrates under normal conditions then the solid methane is released as a gas and expands its volume by nearly 160 times. This instability is what causes methane hydrates to be difficult to study yet so intriguing to scientists as an energy source. But researchers from NTNU’s Nanomechanical Lab as well as researchers from China and the Netherlands used computer simulations to circumnavigate this issue. They found that the size of each hydrate impacted its ability to handle compression/stretching, but not like you would expect. Turns out, smaller hydrates handles those stresses better – up to a point. Hydrates from 15 to 20 nanometers showed the maximum stress load with anything bigger or smaller than that being inferior. As for where you can find these methane hydrates, they can form in gas pipelines and naturally in continental ice shelves as well as below the surface of the ocean (Zhang “Uncovering”, Department).
Anyone dealing with winter conditions knows the perils of slipping on ice. We counter this with materials to either melt the ice or give us additional traction, but is there a material that simply prevents ice from forming on the surface in the first place? Superhydrophobic materials are effective at repelling water rather well, but are usually made with fluoride materials that are not great for the planet. Research from Norwegian University of Science and Technology have developed a different approach. They developed material that lets the ice form but then falls off easily under the slightest break at the micro to nanoscale. This comes from microscopic or nanoscale bumps along the surface that encourage the ice to crack under stress. Now combine this with similar holes along the surface and we have a material which encourages breaks (Zhang “Stopping”).
Slip n’ Side
Speaking of that slipperiness, why does that happen? Well, that’s a complicated topic because of all the different pieces of (mis)information floating about. In 1886, John Joly theorized that contact between a surface and ice generates sufficient heat via pressure to create water. Another theory predicts that friction between the objects form a water layer and makes a reduced frictioned surface. Which one is right? Recent evidence from researchers led by Daniel Bonn (University of Amsterdam) and Mischa Bonn (MPI-P) paints a more complex picture. They looked at frictional forces from 0 to -100 Celsius and compared the spectroscopic results to those theoretical work predicts. Turns out, there are two layers of water on the surface. We have water affixed to the ice via three hydrogen bondings and free-flowing water molecules that are “powered by thermal vibrations” of the lower water. As temperatures increase, those lower water molecule gain freedom to be top layer ones and the thermal vibrations case even faster movement (Schneider).
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Ice forms around 0 Celsius as water cools enough for the molecules to form a solid…sort of. Turns out, that’s true so long as perturbations exist for the excess energy to be dispersed so that the molecules slow enough. But if I take water and keep it very still, I can get liquid water to exist below ) Celsius. Then I can disturb it to create ice. However, this isn’t the same kind we are used to. Gone is the regular crystalline structure and instead we have a material similar to glass, where the solid is really just a tightly (tightly) packed liquid. There is a large scale pattern to the ice, giving it a hyperuniformity. Simulations conducted by Princeton, Brooklyn College, and the University of New York with 8,000 water molecules revealed this pattern, but interestingly the work hinted at two water formats – a high density and low density varieties. Each would give a unique amorphous ice structure. Such studies may offer insights into glass, a common but misunderstood material which also has some amorphous properties (Zandonella, Bradley).
Bradley, David. “Glass inequality.” Materialstoday.com. Elsevier Ltd. 06 Nov. 2017. Web. 10 Apr. 2019.
Department of Energy. “Methane Hydrate.” Energy.gov. Department of Energy. Web. 10 Apr. 2019.
Schneider, Christian. “The Slipperiness of Ice Explained.” Innovaitons-report.com. innovations report, 09 May 2018. Web. 10 Apr. 2019.
Zandonella, Catherine. “Studies of ‘amorphous ice’ reveal hidden order in glass.” Innovations-report.com. innovations report, 04 Oct. 2017. Web. 10 Apr. 2019.
Zhang, Zhiliang. “Stopping problem ice – by cracking it.” Innovations-report.com. innovations report, 21 Sept. 2017. Web. 10 Apr. 2019.
---. “Uncovering the secrets of ice that burns.” Innovations-report.com. innovations report, 02 Nov. 2015. Web. 10 Apr. 2019.
© 2020 Leonard Kelley