{"id":3452,"date":"2021-12-27T22:00:00","date_gmt":"2021-12-27T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=3452"},"modified":"2021-12-09T07:01:14","modified_gmt":"2021-12-09T07:01:14","slug":"this-soft-interface-can-keep-liquid-water-well-below-its-freezing-point","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/this-soft-interface-can-keep-liquid-water-well-below-its-freezing-point\/","title":{"rendered":"This “Soft Interface” Can Keep Liquid Water Well Below Its Freezing Point"},"content":{"rendered":"\n

Ice melts into water; it\u2019s basically a given at this point, at least in the context of everyday life. In fact, the phase transition<\/em> of water from solid to liquid, and finally liquid to gas, is so fundamental to the sciences that it forms the backbone of the Celsius temperature scale; the Swedish astronomer Anders Celsius simply divided the temperature range between when ice melts into water and when water boils into steam into one hundred (100) grades, hence the scale\u2019s older name of the centigrade<\/em> scale.<\/p>\n\n\n\n

Of course, given the years of advancements in science and technology since the creation of the scale back in 1742, we\u2019ve since explored the properties of water with even more detail. We now know that the phase transition temperatures<\/em> of water really depend on pressure, too\u2014it\u2019s why water boils at a lower temperature the higher you go up a mountain.<\/p>\n\n\n\n

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Water, as we well know, boils at 100 \u00b0C, and freezes at 0 \u00b0C. This, however, comes with a caveat: these are its transition temperatures at around Earth\u2019s surface atmospheric pressure. The values differ the higher or lower you go in pressure readings. (Payne, 2019) <\/figcaption><\/figure><\/div>\n\n\n\n

Nowadays, we even have ways of exploring water at its extremes; we\u2019ve seen how it needs \u201cextra heat\u201d to freeze on graphene<\/a>, and how it morphs into a new state called \u201csuperionic ice,\u201d<\/a> a state it takes at extremely high temperatures and pressures.<\/p>\n\n\n\n

Researchers from the University of Houston now have something to add to the constantly-growing list of \u201cspecifically odd things that water does,\u201d as they\u2019ve managed to convince water to stay liquid at temperatures as low as -44 \u00b0C (-47.2 \u00b0F)\u2014that\u2019s 44 degrees in Celsius below zero\u2014all thanks to a special \u201csoft interface.\u201d The results of their unique study was published in the journal Nature Communications<\/em><\/a>.<\/p>\n\n\n\n

These remarkable findings were actually found together with another goal of the study, which was to just examine how water freezes to ice in as much detail as the researchers are capable of achieving.<\/p>\n\n\n\n

In line with this, they designed a porous membrane made of anodized aluminum oxide (Al2<\/sub>O3<\/sub>), whose internal surfaces were coated with octane (C8<\/sub>H18<\/sub>), thus making the surface a \u201csoft interface<\/em>.\u201d They originally wanted to examine just how water turns into ice at the smallest scales by confining the water within pores just 2 nm (nanometers; 2\u00d710-9<\/sup> m; 3.94\u00d710-8<\/sup> in) in diameter.<\/p>\n\n\n\n

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As it turns out, keeping water droplets in contact with oils or lipids in a \u201csoft interface\u201d can keep the water in liquid form well below temperatures where we expect them to start freezing. (University of Houston, 2021) <\/figcaption><\/figure><\/div>\n\n\n\n

And true enough, they managed to see just how water freezes into ice at the smallest scales they could muster. It was here where they also found that some of the water droplets stayed liquid while in contact with the soft interface, despite the temperature readings displaying a frigid -44 \u00b0C (-47.2 \u00b0F).<\/p>\n\n\n\n

This stretches what we know about water droplets, which have been previously known to exhibit a freezing \u201climit\u201d of -38 \u00b0C (-36.4 \u00b0F); at that temperature, any water droplet should have already frozen into ice\u2014or at least that\u2019s how they were understood until this remarkable study came along.<\/p>\n\n\n\n

\u201cWe found that if a water droplet is in contact with a soft interface, freezing temperature could be significantly lower than hard surfaces. Also, a few-nanometer water droplet could avoid freezing down to -44 \u00b0C if it is in contact with a soft interface,\u201d said University of Houston Cullen Associate Professor of Mechanical Engineering Hadi Ghasemi.<\/p>\n\n\n\n

Ghasemi continued: \u201cExperimental probing of freezing temperature of few nanometer water droplets has been an unresolved challenge. Here, through newly developed metrologies, we have been able to probe [the] freezing of water droplets from [a] micron scale down to 2 nm scale.\u201d<\/p>\n\n\n\n

Ghasemi and co-authors believe that their findings can provide valuable insights into how animals can survive in freezing temperatures without experiencing cell death due to freezing, as well as the role that ice plays in climate models and organ preservation.<\/p>\n\n\n\n

References<\/h2>\n\n\n\n