Structure–property correlation of bicyclohexane nematic liquid crystals

Sai, D. Venkata; Zuhail, K. P.; Sarkar, Rudraditya; Dhara, Surajit

doi:10.1080/02678292.2014.987708

Cited by 15 publications

(20 citation statements)

References 32 publications

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“…Considering that the theoretical threshold voltage of (ref. 46), where K 3 is the elastic constant of the bend deformation, is several volts using typical parameters47, the observed V th curve in Fig. 2b is markedly different.…”

Section: Resultsmentioning

confidence: 92%

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Large-scale self-organization of reconfigurable topological defect networks in nematic liquid crystals

et al. 2016

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Topological defects in nematic liquid crystals are ubiquitous. The defects are important in understanding the fundamental properties of the systems, as well as in practical applications, such as colloidal self-assembly, optical vortex generation and templates for molecular self-assembly. Usually, spatially and temporally stable defects require geometrical frustration imposed by surfaces; otherwise, the system relaxes because of the high cost of the elastic energy. So far, multiple defects are kept in bulk nematic liquid crystals by top-down lithographic techniques. In this work, we stabilize a large number of umbilical defects by doping with an ionic impurity. This method does not require pre-patterned surfaces. We demonstrate that molecular reorientation controlled by an AC voltage induces periodic density modulation of ions accumulated at an electrically insulating polymer interface, resulting in self-organization of a two-dimensional square array of umbilical defects that is reconfigurable and tunable.

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Section: Resultsmentioning

confidence: 92%

“…We use the NLC compounds CCN-mn (trans, trans-4, 4′-dialkyl-(1α, 1′α-bicyclohexyl-4β-carbonitriles, Nematel GmbH & Co. KG), which possess a negative dielectric anisotropy47. Particularly, CCN-37 and the 1:1 mixture of CCN-47 and CCN-55 are used in this work because they show the nematic phase at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Large-scale self-organization of reconfigurable topological defect networks in nematic liquid crystals

et al. 2016

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“…This was further confirmed by measuring the dielectric constants in independent planar and homeotropic cells (coated with AL-1254 and JALS-204), respectively. 42 It is observed that in compound CCN-35, there is no noticeable change in dielectric constant during heating and cooling in the nematic phase. In case of CCN-38, CCN-46, and CCN-47, we notice an abrupt decrease of eff in the nematic phase at a particular temperature (T ac ) ( Fig.…”

Section: Resultsmentioning

confidence: 96%

Effect of smectic short-range order on the discontinuous anchoring transition in nematic liquid crystals

Sai

Kumar

Haase

et al. 2014

The Journal of Chemical Physics

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We report studies on the temperature dependent alignment behavior of a homologous series of trans, trans- 4, 4'-dialkyl-(1α,1' α-bicyclohexyl)-4β-carbonitrile (CCNs) on a perfluoropolymer coated cells. Among six compounds in the series, one (CCN-35) has only nematic phase and the remaining five have either smectic-A or smectic-B in addition to the nematic phase. We simultaneously performed temperature dependent dielectric measurements and optical polarising microscope observation. It is found that except for CCN-35 and CCN-73, the remaining four compounds exhibit discontinuous anchoring transition from planar to homeotropic and vice versa with increasing thermal hysteresis. We developed a simple theory taking into account the effect of smectic short-range order at the substrates to explain the experimental observations.

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“…[26] A series of homologue compounds possess negative dielectric anisotropy ∆ϵ = ϵ ∥ − ϵ ⊥ ∼ −5. [27] The symbols ∥, ⊥ denote parallel and perpendicular components to the director. It is also known that the optical anisotropy is relatively low ∆n = n ∥ − n ⊥ ∼ 0.03.…”

Section: Methodsmentioning

confidence: 99%

“…It is also known that the optical anisotropy is relatively low ∆n = n ∥ − n ⊥ ∼ 0.03. [27] We prepare a 50:50 mixture of CCN-47 and CCN-55 which shows nematic phase at room temperature. [28] A small amount of the ionic compound (tetrabutyl anmonium benzoate, Aldrich) is doped into the LC mixtures to induce electrohydrodynamic effects.…”

Section: Methodsmentioning

confidence: 99%

Microscopic characterisation of self-assembled colloidal particles in electrohydrodynamic convection of a low-birefringence nematic liquid crystal

et al. 2015

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Electrokinetics of small particles immersed in anisotropic fluids is attracting attention in recent years. Here we focus on microscopic appearance of single as well as self-assembled particles moving in the electrohydrodynamic convection (EHC) of a nematic liquid crystal with low-birefringence. Characterization of the birefringent properties is made by polarized light microscopy under different illumination conditions. Because of the small optical anisotropy, the director distortion around the particles clearly exhibits distinctive colors on both sides depending on the height in the cell. The observation can be explained as the change in the net phase retardation of the light. It is also found that a caterpillar-like motion is possible by tuning temperature, although the horizontal size of the EHC rolls is relatively narrow.

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Structure–property correlation of bicyclohexane nematic liquid crystals

Cited by 15 publications

References 32 publications

Large-scale self-organization of reconfigurable topological defect networks in nematic liquid crystals

Large-scale self-organization of reconfigurable topological defect networks in nematic liquid crystals

Effect of smectic short-range order on the discontinuous anchoring transition in nematic liquid crystals

Microscopic characterisation of self-assembled colloidal particles in electrohydrodynamic convection of a low-birefringence nematic liquid crystal

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