Saturday, August 25, 2018

Nanotubes can change the shape of water

Insert water in Nanotube hole then The water molecules will align into a square rod, If the nanotube is just the right width. By using molecular models it can be demonstrated that weak van der Waals forces between the inner surface of the nanotube and the water molecules are strong enough to snap the oxygen and hydrogen atoms into place.


According to Molecular models of nanotube ice, water molecules takes the shape of a square tube because of the pressure of a carbon nanotube at left and a boron nitride nanotube  at right.The phenomenon is dependent upon the diameter of the nanotube. It is also known as two-dimensional “ice,” because the molecules freeze regardless of the temperature. To fabricate nanochannels and energy-storing nanocapacitors, The research provides valuable insight on ways to leverage atomic interactions between nanotubes and water molecules 


Boron nitride is best at constraining the shape of water when the nanotubes are 10.5 angstroms wide. The researchers built molecular models of carbon and boron nitride nanotubes with adjustable widths. The hydrogen atoms in tightly confined water take on interesting structural properties. Recent experiments on labs showed and prompted the researchers to build density functional theory models to analyze the forces responsible.

Researchers made 3 angstroms wide water molecules inside carbon and boron nitride nanotubes of various chiralities and the diameter is between 8 and 12 angstroms. They discovered that nanotubes in the middle diameters had the most impact on the balance between molecular interactions and van der Waals pressure that prompted the transition from a square water tube to ice.

If the water molecule is too large as compared to nanotube, the water keeps its amorphous shape. The nanotubes’ van der Waals force starts to push water molecules into organized square shapes.” But at about 8 angstroms  Due to the particular polarization of atoms, the strongest interactions were found in boron nitride nanotubes. Nanotube ice can be used in molecular machines or foster ways to deliver a few molecules of water to targeted cells, like a nanoscale syringe.

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