The Study of Refractive Indices of Liquid Crystal Mixtures

Gharde, Rita A.; Bhave, Manisha G.

doi:10.1080/15421406.2015.1032019

Cited by 10 publications

(4 citation statements)

References 9 publications

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“…However, the N*LCEs exhibited different λ peak at the initial state, and the N*LCE with a mesogenic crosslinker (E-RM82) had a larger value ( Figure 3 b). To investigate the relationship between the chemical systems with mesogenic crosslinkers and the HTP of a chiral agent, we evaluated HTP by using HTP = ( P · c ) −1 and λ peak = n ave · P , where n ave was assumed to be 1.6 [ 43 , 44 , 45 ]. As a result, the HTP values of the N*LCEs were 10.8 µm −1 (E-A6), 10.6 µm −1 (E-A10), and 9.89 µm −1 (E-RM82).…”

Section: Resultsmentioning

confidence: 99%

Effect of Crosslinkers on Optical and Mechanical Behavior of Chiral Nematic Liquid Crystal Elastomers

Hisano

Yuasa

et al. 2021

Molecules

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Chiral nematic (N*) liquid crystal elastomers (LCEs) are suitable for fabricating stimuli-responsive materials. As crosslinkers considerably affect the N*LCE network, we investigated the effects of crosslinking units on the physical properties of N*LCEs. The N*LCEs were synthesized with different types of crosslinkers, and the relationship between the N*LC polymeric system and the crosslinking unit was investigated. The N*LCEs emit color by selective reflection, in which the color changes in response to mechanical deformation. The LC-type crosslinker decreases the helical twisting power of the N*LCE by increasing the total molar ratio of the mesogenic compound. The N*LCE exhibits mechano-responsive color changes by coupling the N*LC orientation and the polymer network, where the N*LCEs exhibit different degrees of pitch variation depending on the crosslinker. Moreover, the LC-type crosslinker increases the Young’s modulus of N*LCEs, and the long methylene chains increase the breaking strain. An analysis of experimental results verified the effect of the crosslinkers, providing a design rationale for N*LCE materials in mechano-optical sensor applications.

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Section: Resultsmentioning

confidence: 99%

Effect of Crosslinkers on Optical and Mechanical Behavior of Chiral Nematic Liquid Crystal Elastomers

Hisano

Yuasa

et al. 2021

Molecules

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“…where T is the temperature; P is the helical pitch; and n av (T) is the average refractive index of the mixture. The birefringence ∆n(T), the extraordinary refractive index n e (T), and the average refractive index n av (T) can be expressed as [24][25][26]:…”

Section: Resultsmentioning

confidence: 99%

A Tunable NIR Filter with Sphere Phase Liquid Crystal

Sun

2019

Crystals

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A near-infrared (NIR) filter with sphere phase liquid crystal (SPLC) is proposed, which shows a low operating electric field and large temperature-gradient modulations. The central wavelength of the Bragg reflection can be thermally tuned from 1580 nm to 1324 nm with a temperature-gradient of 42.7 nm/K. Meanwhile, the central wavelength can be electrically tuned over 76 nm within a low operating electric field of 0.3 V/μm. Thus, the SPLC filter may achieve a wavelength variation of 256 nm by thermal modulation and 76 nm by electrical modulation. The SPLC filter shows great potential applications in optical communication devices.

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“…In uniaxial LCs, the incoming light wave after entering the anisotropic LC medium splits into an ordinary ray polarized parallel to the nematic director and an extraordinary ray polarized perpendicular to the director. When the two rays recombine as they exit the LC medium, the retardation or phase shift results in a different polarization state of the transmitted light [248].…”

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confidence: 99%

“…[248] Organic rod-like molecular LCs are stiff extended molecules often with extended 𝜋-conjugated double bonds. Because of this various models such as the Lorentz-Lorenz equation and Cauchy equation, which are common for isotropic liquids, need to be modified before they can be used for organic LCs to evaluate the RI dependencies as a function of wavelength and temperature [251].…”

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Crystalline Titania Nanorods for Colloidal Liquid Crystal Based Switchable Optics

Nohoji¹

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Liquid crystalsLiquid crystals (LCs) are typically associated with the development of various LCbased displays (LCDs) such as flat-panel televisions, touchscreen displays, and computer monitors used in our daily lives. Besides massive achievements in the field of LCDs over the last decades, [1] LCs have also attracted attention in a broad range of non-display applications from telecommunication technologies, photonics, sensors, and medicine to self-assembled amphiphilic soap molecules, which are on the borderline between soft condensed matter and nanotechnology. [2][3][4] This class of matter is of great interest mainly due to its fascinating anisotropic properties (i.e., refractive index, viscosity, elastic constant, electric conductivity, or magnetic susceptibility) that can be manipulated via responses to applied external stimuli (i.e., mechanical, electric, magnetic, or even optical stimuli) or their spontaneous self-organization.[1,5] Nowadays, many optical applications benefit from the elastic behavior of LCs (specifically commercial thermotropic LCs) which can be tuned via electric or magnetic fields. The alteration in the orientation of the mesogens in these LCs changes the orientation of the optical axis, resulting in birefringence. Several effects of the anisotropic properties of LCs with polarized light are reproduced from references [6,7] and shown in Figure 1-1.In general, LCs are referred to as intermediate phases or mesophases formed by elongated building blocks or mesogens which can be organic, inorganic, or organometallic compounds. These mesophases are thermodynamically stable and located between the three-dimensional solid crystal and the viscous liquid, which is an isotropic disordered phase. Therefore, LCs are characterized by long-ranged orientational order, which can be combined with long-ranged positional order in one or two dimensions of their long mesogens axis, resulting in direction-dependent physical properties analogous to crystalline solids whereas the ability to flow and long-ranged diffusion is preserved similar to fluids. [8] Although some liquid crystalline properties were observed and described by several researchers more than 100 years ago, thermotropic LCs were not realized until 1888 when Reinitzer[9] discovered this state of matter, which was followed by Lehmann[10] in 1889 who assigned the term 'thermotropic liquid crystals' to these mesophases (the references are in German). [11] In general, two main classes of LCs are distinguished: thermotropic within the layers and at the same time stand parallel to the layer's normal director, the smectic phase is called smectic-B. If the hexagonal order inside the layers exhibits a longrange positional order, the structure will be therefore a three-dimensional crystal. [12] Likewise, the aforementioned LC phases are observed in lyotropic LCs, however, due to the nature of these mesophases, they are formed when the concentration of the anisotropic mesogens is raised to a high enough value. If anisotropic molecular mesogens form lyotr...

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The Study of Refractive Indices of Liquid Crystal Mixtures

Cited by 10 publications

References 9 publications

Effect of Crosslinkers on Optical and Mechanical Behavior of Chiral Nematic Liquid Crystal Elastomers

Effect of Crosslinkers on Optical and Mechanical Behavior of Chiral Nematic Liquid Crystal Elastomers

A Tunable NIR Filter with Sphere Phase Liquid Crystal

Crystalline Titania Nanorods for Colloidal Liquid Crystal Based Switchable Optics

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