Evolution of the Phase Transition in the Nematic Phase of a Liquid Crystal Doped with Metallic Nanoparticles
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Polymer-dispersed liquid crystal (PDLC) films containing nanosized droplets of nematic liquid crystal (NLC) with metallic nanoparticle (NP) additives were investigated for potential use in display devices. Polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) methods showed that PDLC films with low concentrations of NPs significantly alter the optical properties (transmission coefficient, threshold voltage, contrast and absorption coefficients) of the materials under study. It was found that, with a constant UV irradiation intensity, the dye concentration can be optimized to ensure uniform droplet size, higher light transmission, and increased contrast coefficient. Using the Beer-Lambert equation, absorption and extinction coefficients were obtained by measuring the light transmission of PDLC films. It was discovered that the liquid crystal droplets in the PDLC films predominantly adopt a bipolar configuration. A higher content of metallic nanoparticles leads to a decrease in the clearing temperature and a reduction in light transmission due to the lowered order parameter caused by thermal fluctuations. Numerical calculation results showed that the maximum contrast coefficient for PDLC films with nanoparticle content is 2.55 times higher than the minimum contrast coefficient of the films in their initial state. Possible mechanisms for the implementation of these results have been proposed for the creation of flexible liquid crystal display elements used in environmentally friendly technologies.
Egamov, M.Kh., Maksudov, B.I., Faizulloev, I.Kh. Hysteresis phenomena and the effect reorientation in a polymer-liquid crystal system under the influence of laser radiation and uniaxial deformation // Journal of Physics: Conference Series. 2022. V. 2270 – 012011. DOI: 10.1088/1742-6596/2270/1/012011
Drzaic, P. S. Polymer dispersed nematic liquid crystal for large area displays and light valves // Journal of Applied Physics. American Institute of Physics. 1986. Vol. 60, No. 6. - p. 2142–2148.
Egamov, M.Kh., Maksudov, B.I., Faizulloev, I.Kh. Optical hysteresis in composites based on polymer-nematic liquid crystal under uniaxial deformation // Russian Physics Journal, 2022, Vol. 65, №3. – p. 488-492.
Zharkova, G.M., Sonin, A.S. Liquid Crystal Composites. Novosibirsk: Nauka, 1994. – 224 p.
Zyryanov, V.Ya., Krahalev, M.N., Pritschepa, O.O., Shabanov, A.V. Orientation-structural transitions in nematic droplets due to ionic modification of the interphase boundary under the influence of an electric field // Letters to JETP, 2007, Vol. 86, Issue 6. – pp. 440-445.
Loyko, V.A., Zyryanov, V.Ya., Konkolovich, A.V., Miskevich, A.A. Light transmission through a polymer-coated liquid crystal layer with heterogeneous adhesion on the surface of droplets // Optics and Spectroscopy, 2026, Vol. 120, No. 1. – pp. 158-168.
Farzana Ahmad, Muhammad Jamil, Young Jae Jeon, Lee Jin Woо, Jae Eun Jung, Jae Eun Jang. Investigation of nonionic diazo dye-doped polymer dispersed liquid crystal film //Вull. Mater. Sci. 2012, Vol. 35, No. 2. - p. 221–231.
Joachim Jelken, Carsten Henkel, Svetlana Santer. Formation of half-period surface relief gratings in azobenzene containing polymer films. // Applied Physics B. 2020. V. 113 – p. 126-149.
Aphonin, O. Optical properties of stretched polymer dispersed liquid crystal films: Angle dependent polarized light scattering // Liquid Crystals. 1995. Vol. 19, No. 4. -p. 469–480.
Zyryanov, V.Ya., Smorgon, S.L., Shabanov, A.V., Pozhidaev, E.P. Optimization of contrast, brightness, and light modulation amplitude in electro-optical devices based on polymer-capsulated ferroelectric liquid crystals // Letters to JETP, 1998, Vol. 24, No. 12. – pp. 63-67.
