Nematic-isotropic interface of some members of the homologous series of 4-cyano-4′-(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-alkyl)biphenyl liquid crystals

Faetti, Sandro; Palleschi, Vincenzo

doi:10.1103/physreva.30.3241

Cited by 142 publications

(79 citation statements)

References 38 publications

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“…It is by 1-2 orders more than Ws for homologous series of 4-cyano-4'-(n-alkyl)biphenyls at the interface with the own isotropic phase [29] where the tilted anchoring was observed. The estimation of the surface extrapolation length ξ = K / Ws, where K = (K11 + K33) / 2, showed that ξ = (K11+K33) / (4.8 K22) ~ 1 m for the structure under study.…”

Section: Discussionmentioning

confidence: 92%

Director configurations in nematic droplets with tilted surface anchoring

et al. 2016

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The polymer dispersed nematic liquid crystal with the tilted surface anchoring has been studied. The droplet orientational structures with two point surface defects-boojums and the surface ring defect are formed within the films. The director tilt angle  = 40  4 at the droplet interface and LC surface anchoring strength Ws ~ 10 -6 (J m -2 ) have been estimated. The bipolar axes within the studied droplets of oblate ellipsoidal form can be randomly oriented are oriented randomly relatively to the ellipsoid axes as opposed to the droplets with homeotropic and tangential anchoring.

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Section: Discussionmentioning

confidence: 92%

Director configurations in nematic droplets with tilted surface anchoring

et al. 2016

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“…Moreover, a demixing would lead to huge interfacial areas in the confined geometry, given the large specific surface areas of the mesoporous hosts. Therefore, the corresponding energetic costs of fluid/fluid interfaces and of isotropic-nematic interfaces (because of the distinct T I N of the single components) may be non negligible and additionally contribute to a suppression of any demixing, despite the quite small magnitude of the specific interfacial tensions of the liquid/liquid (a few mN/m) and of the isotropic-nematic interfaces (on the order of 10 −2 mN/m) [49,50].…”

Section: Fig 6: (Color Online) Nematic Ordering Field σ Vs Mole Framentioning

confidence: 99%

Paranematic-to-nematic ordering of a binary mixture of rodlike liquid crystals confined in cylindrical nanochannels

et al. 2014

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We explore the optical birefringence of the nematic binary mixtures 6CB1−x7CBx (0 ≤ x ≤ 1) imbibed into parallel-aligned nanochannels of mesoporous alumina and silica membranes for channel radii of 3.4 ≤ R ≤ 21.0 nm. The results are compared with the bulk behavior and analyzed with a Landau-de-Gennes model. Depending on the channel radius the nematic ordering in the cylindrical nanochannels evolves either discontinuously (subcritical regime, nematic ordering field σ < 1/2) or continuously (overcritical regime, σ > 1/2), but in both cases with a characteristic paranematic precursor behavior. The strength of the ordering field, imposed by the channel walls, and the magnitude of quenched disorder varies linearly with the mole fraction x and scales inversely proportional with R for channel radii larger than 4 nm. The critical pore radius, Rc, separating a continuous from a discontinuous paranematic-to-nematic evolution, varies linearly with x and differs negligibly between the silica and alumina membranes. We find no hints of preferred adsorption of one species at the channels walls. By contrast, a linear variation of the nematic-to-paranematic transition point TPN and of the nematic ordering field σ vs. x suggest that the binary mixtures of cyanobiphenyls 6CB and 7CB keep their homogeneous bulk stoichiometry also in nanoconfinement, at least for channel diameters larger than ∼7 nm.

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“…Further, as explained in ref. [14], the anchoring of the director at the I-N interface [24] forces the director to lie on a cone, with the half angle equal to about 64 0 . This forces the order parameter space there to become effectively a circle S 1 , instead of being RP 2 , with the order parameter being an angle between 0 and 2π.…”

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confidence: 99%

Measuring cosmic defect correlations in liquid crystals

Srivastava

Ray

2004

Phys. Rev. D

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From the theory of topological defect formation proposed for the early universe, the so called Kibble mechanism, it follows that the density correlation functions of defects and anti-defects in a given system should be completely determined in terms of a single length scale ξ, the relevant domain size, which is proportional to the average inter-defect separation r av . Thus, when lengths are expressed in units of r av , these distributions should show universal behavior, depending only on the symmetry of the order parameter, and space dimensions. We have verified this prediction by analyzing the distributions of defects/anti-defects formed during the isotropic-nematic phase transition in a thin layer in a liquid crystal sample. Our experimental results confirm this prediction and are in reasonable agreement with the results of numerical simulations.

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Nematic-isotropic interface of some members of the homologous series of 4-cyano-4′-(n-alkyl)biphenyl liquid crystals

Cited by 142 publications

References 38 publications

Director configurations in nematic droplets with tilted surface anchoring

Director configurations in nematic droplets with tilted surface anchoring

Paranematic-to-nematic ordering of a binary mixture of rodlike liquid crystals confined in cylindrical nanochannels

Measuring cosmic defect correlations in liquid crystals

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