Liquid crystals in nanopores produce a surprisingly large negative pressure

phys.org | 4/12/2019 | Staff
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Negative pressure governs not only the Universe or the quantum vacuum. This phenomenon, although of a different nature, appears also in liquid crystals confined in nanopores. At the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, a method has been presented that for the first time makes it possible to estimate the amount of negative pressure in spatially limited liquid crystal systems.

At first glance, negative pressure appears to be an exotic phenomenon. In fact, it is common in nature, and what's more, occurs on many scales. On the scale of the universe, the cosmological constant is responsible for accelerating the expansion of spacetime. In the world of plants, attracting intermolecular forces guarantee the flow of water to the treetops of all trees taller than ten metres. On the quantum scale, the pressure of virtual particles of a false vacuum leads to the creation of an attractive force, appearing, for example, between two parallel metal plates (the famous Casimir effect).

Fact - Pressure - Liquid - Crystals - Nanopores

"The fact that a negative pressure appears in liquid crystals confined in nanopores was already known. However, it was not known how to measure this pressure. Although we also cannot do this directly, we have proposed a method that allows this pressure to be reliably estimated," says Dr. Tomasz Rozwadowski from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow, the first author of a publication in the Journal of Molecular Liquids.

The Polish physicists investigated a liquid crystal known as 4CFPB, made up of 1.67 nm long molecules with a molecular diameter of 0.46 nm. Experiments without nanopores, under normal and elevated pressure conditions (up to around 3000 atmospheres), were carried out at the University of Silesia in Katowice. In turn, systems in silicon membranes with non-intersecting nanopores with a diameter of...
(Excerpt) Read more at: phys.org
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