Effect of a Trifluorophenyl-Based Monomer on the Electro-optic Performances of Polymer-Stabilized Blue Phase Liquid Crys
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Effect of a Trifluorophenyl-Based Monomer on the Electro-optic Performances of Polymer-Stabilized Blue Phase Liquid Crystals Minggang Hu 1 & Jiangwei Li 1 & Nejmettin Avci 2 Received: 24 June 2020 / # Sociedade Brasileira de Física 2020
Abstract We synthesized one novel mono-functional acrylate monomer. The effect of the new monomer on blue phase liquid crystal stabilization and electro-optical properties was investigated with different reactive polymer concentration and combination. The temperature range of blue phase samples was widened over 50 ° C including room temperature through the use of polymer stabilization. Electro-optical properties including lower driving voltage (69.8 V), lower hysteresis (3.9%), lower response time (0.468 ms), and higher Kerr constant (9.4 nm/V2) were obtained by optimizing the concentration of different composites. They are strongly influenced by the interface energy between the liquid crystal molecules and polymer combination system. It is found that hysteresis is sensitive to the polymer concentration. Keywords Polymer blue phase . Liquid crystal . Monomer . Response time . Hysteresis . Kerr constant
1 Introduction Blue phases (BPs) are usually found only in a narrow temperature range of a few degrees between the isotropic liquid and the helical cholesteric phases with a relatively short helical pitch [1, 2]. In general, they can be divided into three distinct thermodynamic phases depending on the double-twisted cylinder packing structure (neighboring molecules slightly twist into each other to constitute a helicoidal twist) as functions of temperature and chirality: blue phase I (BP I), blue phase II (BP II), and blue phase III (BP III). The packing structure of BPI and BPII is body-centered cubic lattice and simple cubic lattice, respectively. In contrast, BPIII possesses almost the same symmetry as the isotropic phase. BPs are potentially considered as candidate materials for next-generation electro-optic and photonic application owing to the electrically controllable Bragg diffraction of visible light such as fast optical shutters and photonic applications [3, 4]. Since they show fast electro-optic effect characterized by optical switching between isotropic and anisotropic states, * Nejmettin Avci [email protected] 1
Xi’an Modern Chemistry Research Institute, Xi’an, China
2
Faculty of Science, Department of Physics, Mugla Sitki Kocman University, 48000 Kotekli, Mugla, Turkey
nevertheless, their narrow temperature range is an important problem. To date, tremendous research efforts have been successfully made to broaden the temperature range of BPs as well as to shift them towards the room temperature. The first successful experimental approach was reported by Kikuchi et al. [4]. A small amount of specific reactive monomer (∼ 10 wt%) tends to selectively concentrate in the lattice disclination lines of the BP and hence stabilize the overall cubic lattice against the temperature variation and electrical field. Therefore, the temperature range of the polymers
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