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А. S. Merekalov¹*, O. N. Karpov^1,2, Yu. A. Egorov¹, A. S. Plotnikova¹, S. А. Legkov¹, G. N. Bondarenko¹, R. V. Talroze^1,2

Author affiliations
¹A. V. Topchiev Institute of Petrochemical Synthesis RAS, Moscow, Russia
²Lomonosov Moscow State University, Department of Physics, Moscow, Russia
*Corresponding author: rtalroze@ips.ac.ru, alexis@ips.ac.ru

Abstract
In this work, the relaxation process in mixtures of a nematic liquid crystal as a matrix with additives of azochromophores and CdSe/ZnS quantum dots is analyzed. Thermally initiated mesophase – isotropic liquid phase transition showed that the activation energy of this process increases almost equally upon addition of AX-7 or AX-8 in amount of 10 wt. %. However, the photoinduced phase transition into isotropic state, which was analyzed by dielectric spectroscopy, demonstrates a significant difference when different azochromophores are present in the system. That was confirmed by activation energy values. This effect is associated with a change in the ratio of trans-cis-isomers. IR-spectroscopy data revealed an unexpected fact of the predominance of cis-isomers in AX-7. Trans-isomers are typical for AX-8. This difference was explained by a change in the distribution of electron density in azochromophore fragments, taking into account the influence of aromatic ring substituents.

Keywords: liquid crystal, azochromophore, IR-spectroscopy, dielectric spectroscopy