Enlargement of blue-phase stability for rod-like low-molecular-weight chiral nematic liquid crystal mixtures

Kim, Beomjong; Um, Yeon Jung; Jeon, Seongun; Kikuchi, Hirotugu; Hong, Sung Kyu

doi:10.1080/02678292.2014.936531

Cited by 5 publications

(3 citation statements)

References 23 publications

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“…It is experimentally found that during cooling the existence of BPs has been observed in a wide temperature range about (9-15°C). This positive property can enable application of BPs in practice (for instance, for studies of colloidal particles in BPs [67] at nearroom temperature), as compared to the most wellknown pure thermotropic cholesterics and their mixtures, possessing BPs in narrow temperature ranges (0.5-2°C), that recently leaded to searches of new classes of the CLCs, possessing on the one hand, a wide temperature range of the blue phase, [40][41][42][43][44][45][46][47][48][49][50][51][52][53] in particular bimesogens, PS-BPLC or BPTN, [23,[25][26][27][28][29]33,39] and on the other hand CLCs, having BPs at low temperatures (i.e. at near-room temperature).…”

Section: Resultsmentioning

confidence: 97%

“…BPs with a wide temperature range (about 30°C) and electric-field-induced transitions for binaphthyl derivative was studied in. [48] As shown in, [49] the usage of the rod-like low-molecular weight cyano homologue chiral nematic LCs with various core groups and concentrations of ChD lead to the stable BP temperature range (more than 13.5°C) on heating and cooling and fast response (less than 1 ms). The influence of number chiral mesogenic units and spatial arrangement on BP induction and stability, by using benzene derivatives possessing various helical twisting power (HTP), was investigated in.…”

Section: Introductionmentioning

confidence: 98%

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‘Blue phases’ of highly chiral thermotropic liquid crystals with a wide range of near-room temperature

Gvozdovskyy

2015

Liquid Crystals

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To cite this article: Igor Gvozdovskyy (2015): 'Blue phases' of highly chiral thermotropic liquid crystals with a wide range of near-room temperature, Liquid Crystals,The phase transitions of pure cholesteric liquid crystals, based on right-or left-handed chiral dopants (ChDs) (enantiomers R-811 and S-811, Merck, Darmstadt, Germany) with various concentrations dissolving in the nematic liquid crystal mixture CHCA (ZhK-805, Russia, NIOPIK) were experimentally studied. For the first time, blue phases of cholesterics were found at the concentration range of ChDs 32-36 wt.%. Experimentally it was observed that during the cooling process the blue phase of cholesterics is stable over a wide temperature range about~15°C including human body and near-room temperatures. Thermal phase transitions, spectral characteristics and electro-optical features of blue phases were examined. Planar and homeotropic alignment layers were used to study the influence of various boundary conditions on platelet textures of blue phases. IntroductionIt is known that for certain chiral liquid crystals (CLCs) and their mixtures the transition between the regular (helical) cholesteric phase (Ch) and the isotropic phase (Iso) occurs through a series of additional transitions well known as 'blue' phases (BPs), [1-9] which in most cases can exist only for cholesterics with pitch P < 5000 Å.[5,10] Within a narrow temperature range three thermodynamically stable blue phases (BP-III, BP-II and BP-I) exist, which can be usually observed on cooling from Iso to Ch, but sometimes on heating from Ch to Iso [3,9,11] and vice versa with thermal hysteresis. [11][12][13] The so-called 'fog' blue phase (BP-III) is amorphous with a local cubic lattice structure in the director field, which appears over a very narrow temperature range between BP-II and the Iso,[3,14-17] while BP-II and BP-I have a fluid three-dimensional periodic structure in the director field with simple cubic and body-centred cubic symmetry, respectively. [6][7][8]15,16,18] For BP-I the elementary cell (lattice) size changes with temperature; while for BP-II there is not temperature change in the lattice size. [19] According to the theory,[19] structures of BPs can be described as 'double twist' cylinders (in which the director twists simultaneously in two independent directions), filling up large volumes and disclinations. The fact that the periods of lattices of BP-II and BP-I are of the order of the visible wavelength region, leads to the observation of the selective Bragg diffraction. In addition, BPs are optically active but, unlike Ch,

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

‘Blue phases’ of highly chiral thermotropic liquid crystals with a wide range of near-room temperature

Gvozdovskyy

2015

Liquid Crystals

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“…В одних случаях это приводит к понижению вяз-кости систем, что сказывается на быстродействии электрооптических устройств, и к снижению рабо-чего напряжения, в других -к увеличению конт-раста и улучшению электрооптических характе-ристик. Несомненный интерес в последнее время вызывает исследование жидкокристаллических материалов, допированных оптически активными соединениями [27]. Исходя из этого, нами были проведены исследования диэлектрических свойств цианобифенила с гидроксилсодержащим хираль-ным терминальным заместителем S-МГПЦБ и жидкокристаллической смеси НО-3-ЦБ 90 % + S-МГПЦБ 10 %, результаты которых представлены на рис.…”

Section: диэлектрические свойстваunclassified

Synthesis and Properties of Mesogens Containing Chiral Terminal Substituent with Hydroxy Group

Kuvshinova¹,

Gorshkova²,

Новиков³

et al. 2017

Liq. Cryst. and their Appl.

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Blue phase liquid crystal phase transition for cyano compound chiral nematic liquid crystal mixtures with three two-ring core structures and chiral dopant concentrations

et al. 2016

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Enlargement of blue-phase stability for rod-like low-molecular-weight chiral nematic liquid crystal mixtures

Cited by 5 publications

References 23 publications

‘Blue phases’ of highly chiral thermotropic liquid crystals with a wide range of near-room temperature

‘Blue phases’ of highly chiral thermotropic liquid crystals with a wide range of near-room temperature

Synthesis and Properties of Mesogens Containing Chiral Terminal Substituent with Hydroxy Group

Blue phase liquid crystal phase transition for cyano compound chiral nematic liquid crystal mixtures with three two-ring core structures and chiral dopant concentrations

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