Researchers from the Massachusetts Institute of Technology have found a way to freeze water at boiling temperatures, a recent study in the journal Nature Nanotechnology reports.
Though water normally begins to boil at 212 degrees Fahrenheit, past studies have shown that confining the liquid to small spaces can alter its boiling and freezing points by a small margin. This new study expands on this property by allowing water to freeze solid when it is at high temperatures.
The team accomplished this by trapping water inside carbon nanotubes no bigger than a few molecules across. The researchers found that the behavior of familiar materials can be altered when stuffed into small spaces.
“If you confine a fluid to a nanocavity, you can actually distort its phase behavior,” explained study co-author Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT, in a statement.
While the results of the study were expected, researchers did not foresee just how much change was going to occur. In one of the trials, the researchers were able to freeze water at a temperature above 220 degrees Fahrenheit.
“The effect is much greater than anyone had anticipated,” added Strano.
Carbon nanotubes are molecular structures shaped like soda straws. They are made entirely of carbon atoms and measure only a few nanometers in diameter.
In the study, the team created tubes that were open at both ends and then placed water at each opening. This revealed that in terms of changing the properties of water, the diameter of the nanotube is critical. A change as small as .01 nanometer can make a difference of tens of degrees in the water’s freezing point.
The team recorded this behavior using a highly sensitive imaging process known as vibrational spectroscopy. This allowed them to map the liquid while it was inside the tubes — something that had not been possible in the past. In addition, they were able to see the different phases of water as it moved through the structures, Phys.org reports.
This discovery could have many future applications. For instance, it could lead to more efficient energy transfer because water conducts protons 10 times better than current conductive materials.
Before that happens, however, many questions still need to be answered. Early trials came up with contradictory results — mainly because it was hard to measure the exact sizes of the nanotubes — and researchers are not sure why water enters the tubes at all. The straw-like structures are supposed to be hydrophobic, meaning they should repel water. However, they readily accept it.
“All bets are off when you get really small,” added Strano. “It’s really an unexplored space.”