It is well known that the boiling point of water, at sea level, is 100 degrees Celsius, while in the mountains the transition from liquid to gas occurs at a temperature lower because of the lower atmospheric pressure. MIT scientists have now discovered that water becomes solid at high temperatures when confined in carbon nanotubes. This opens the door to a variety of applications that exploit the physical and chemical properties of ice.
The researchers showed that water molecules exhibit a different behavior if trapped inside nanoscale structures. The phenomenon by which the freezing and boiling points of change if the fluid is confined in a nano-cavities was already known, but as discovered by the MIT is a real surprise, since the freezing point is increased rather than decreased. In one of the tests performed in the laboratory, water has become solid at a temperature of 105 degrees Celsius . The team of scientists also noted other “oddities.”
The freezing point is extremely dependent on the diameter of the carbon nanotubes (a carbon atom thick sheets rolled so as to form a cylinder). It is sufficient in fact a variation of 0.01 nanometers to increase or decrease the temperature of 10 degrees. Carbon nanotubes are water repellent (hydrophobic), so it is not clear how the water molecules can enter. To detect the presence of water in nanotubes and its phase (liquid, solid or gaseous) is a technique known as vibrational spectroscopy was used.
Carbon nanotubes with frozen water could be used as “ ice wires “. The water may in fact lead protons up to 10 times more easily than other materials. The research was published in the journal Nature Nanotechnology.