25 May, 2020 18:01

Scientists determine properties of liquid crystals that might help create electronic paper

Source: TASS
Scientists from Siberian Federal University and Siberian Branch of the Russian Academy of Sciences (Institute of Physics (Federal Research Center, Krasnoyarsk) determined the structural peculiarities of liquid crystals, thanks to which the material can be used to create "smart windows" and electronic notebooks in the future, TASS reported on Thursday citing the press service of Siberian Federal University.

"Scientists were the first in the world to study the orientational structures of cholesteric liquid crystals embedded in a polymer sheet with conical boundaries. The main configurations of the director and the forming defects that determine the electro-optical properties of these materials were identified in such drops. The authors believe that composite materials that can be created based on such liquid crystals, can be widely used in 'smart windows', electronic paper and new generation lasers,” the SFU press service said.

The internal structure of liquid crystals which lacks symmetry is called cholesteric — each layer of molecules is at an angle with respect to the neighboring one, and a spiral forms as a result. They have unique electro-optical properties and in the future, as part of polymer sheets, can become the basis of "smart windows" that regulate a room's illumination, as well as ultra-thin electronic paper. In order to do so, the scientists need to thoroughly study the structure of the material and identify those features due to which it acquires useful properties. The authors of the study became the first in the world to conduct a study of the orientational structure of cholesteric liquid crystals and determined the characteristics defining their unique properties.

The researchers examined the dependence of structure properties on the size of liquid crystal drops in a sheet in particular. The experiments showed that the drop's diameter is associated with the orientation structure formed by the liquid crystal in the sheet — it can be twisted or layered. Information on the exact parameters of the formation of different structures of liquid crystals is important for the development of composite materials based on them with the required properties that can change their optical properties under the impact of an electric field.

"Moreover, it turned out that between these 'extreme' stages a special transitional structure occurs in which the symmetry has already been broken, but no layers have yet developed, this is one of our discoveries," said Anna Gardymova, associate professor of the Department of Instrument Engineering and Nanoelectronics of the Siberian Federal University. 

The use of technologies such as "smart windows" or electronic paper will allow to save natural resources by giving up deforestation and will also help reduce energy consumption, the authors of the study say. The results of the study supported by the Russian Science Foundation (RSF) are published in the journal Molecules.

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