Water at boiling point freezes to ice in carbon nano tubes
MIT,Nov30:Scientists know that water boils at 100 degrees Celsius and turns into ice at zero degree Celsius at sea level. The conversion of state can be altered by 10 degrees Celsius by applying some pressure or confining water in a small area.
However, a team of scientists at MIT have discovered another property of water which was not known till date. Researchers used carbon nanotubes whose inner dimensions measure few water molecules. They dropped few drops of water in those tubes and found that water turned into ice and remained in that state even at higher temperatures where water starts boiling in normal conditions.
Such property of water was hidden till date and it is a proof that well-known substance can dramatically change its behaviour in different conditions, especially when trapped within nanotubes.
Michael Strano, the Carbon P. Dubbs Professor in Chemical Engineering at MIT, explained that confining a fluid to a nanocavity can actually distort its phase behaviour and can change freezing and boiling point of the substance by a great amount. While testing, researchers found that water to be in solid state at 105 C and they believe that water could have maintained this state at 151 C. It is to be noticed that water boils at 100 C in normal conditions and it is for the first time that scientists have recorded such behaviour of water.
Strano revealed that these nanotubes are smallest tubes in diameter, even smaller than your imagination. Water took the shape of soda straw when inserted in carbon nanotubes.
He further added that diameter of nanotube has a major impact on the behaviour of water. Even minute difference in diameter (1.05 nanometers and 1.06 nanometers) can lead to the variation of ten degrees in the boiling point and freezing point.
What’s striking is that researchers not only actively detected the presence of water in the tube but also were able to detect its phase. Water goes into solid state in tube and forms a crystalline structure. Study authors pointed out that water does not convert into ice but forms ice-like phase in nanotubes.
Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure as per Wiki. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material.
In addition, owing to their extraordinary thermal conductivity, mechanical, and electrical properties, carbon nanotubes find applications as additives to various structural materials. For instance, nanotubes form a tiny portion of the material(s) in some (primarily carbon fiber) baseball bats, golf clubs, car parts or damascus steel.
The find can be used to make ice wires at room temperature which will be the best carrier for proton. It is to be noticed that water is 10 times better for conducting protons when compared to other conductive materials.
The study appeared in the journal Nature.