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We have studied the effects of quenched random disorder created by dispersed aerosil nanoparticle gels on the nematic to smectic-A (N-SmA) and smectic-A to reentrant nematic (SmA- RN) phase transitions of thermotropic liquid crystal…

Soft Condensed Matter · Physics 2009-11-13 M. Ramazanoglu , S. Larochelle , C. W. Garland , R. J. Birgeneau

The effects of dispersed aerosil nanoparticles on two of the phase transitions of the thermotropic liquid crystal material 4-n-pentylphenylthiol-4'-n-octyloxybenzoate 8barS5 have been studied using high-resolution x-ray diffraction…

Soft Condensed Matter · Physics 2009-11-10 P. S. Clegg , R. J. Birgeneau , S. Park , C. W. Garland , G. S. Iannacchione , R. L. Leheny , M. E. Neubert

High-resolution X-ray scattering studies of the nonpolar thermotropic liquid crystal 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (\bar{8}S5) in aerosil gel nano-networks reveal that the aerosil-induced disorder significantly alters both the…

Soft Condensed Matter · Physics 2015-05-28 B. Freelon , M. Ramazanoglu , P. J. Chung , P. Valdivia , C. W. Garland , R. J. Birgeneau

Comprehensive x-ray scattering studies have characterized the smectic ordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica gels formed by aerosil dispersions. For all densities of aerosil and all measurement…

Soft Condensed Matter · Physics 2009-11-07 R. L. Leheny , S. Park , R. J. Birgeneau , J. -L. Gallani , C. W. Garland , G. S. Iannacchione

The effect on the nematic to smectic-A transition in octylcyanobiphenyl (8CB) due to dispersions of hydrogen-bonded silica (aerosil) particles is characterized with high-resolution x-ray scattering. The particles form weak gels in 8CB…

Soft Condensed Matter · Physics 2009-11-07 S. Park , R. L. Leheny , R. J. Birgeneau , J. -L. Gallani , C. W. Garland , G. S. Iannacchione

We report a high-resolution x-ray scattering study of the smectic liquid crystal octylcyanobiphenyl (8CB) confined to aligned colloidal aerosil gels. The aligned gels introduce orientational fields that promote long-range nematic order…

Disordered Systems and Neural Networks · Physics 2015-06-25 Dennis Liang , Robert L. Leheny

We study the smectic AC transition in anisotropic and uniaxial disordered environments, e.g., aerogel with an external field. We find very strange behavior of translational correlations: the low-temperature, lower-symmetry Smectic C phase…

Exactly Solvable and Integrable Systems · Physics 2009-11-10 Leiming Chen , John Toner

Optical birefringence measurements on a rod-like liquid crystal (8OCB), imbibed in silica channels (7 nm diameter), are presented and compared to the thermotropic bulk behavior. The orientational and positional order of the confined liquid…

Soft Condensed Matter · Physics 2015-05-20 Andriy V. Kityk , Patrick Huber

We present a neutron scattering analysis of the structure of the smectic liquid crystal octylcyanobiphenyl (8CB) confined in one-dimensional nanopores of porous silicon films (PS). The smectic transition is completely suppressed, leading to…

Soft Condensed Matter · Physics 2016-08-16 Régis Guégan , Denis Morineau , Claude Loverdo , Wilfried Béziel , Mohammed Guendouz

Liquid crystals offer many unique opportunities to study various phase transitions with continuous symmetry in the presence of quenched random disorder (QRD). The QRD arises from the presence of porous solids in the form of a random gel…

Soft Condensed Matter · Physics 2009-11-07 Germano S. Iannacchione , Sungil Park , Carl W. Garland , Robert J. Birgeneau , Robert L. Leheny

We study a model for the Nematic--Smectic-A (NA) transition in aerogel, and find that even arbitrarily weak quenched disorder (i.e., low aerogel density) destroys translational (smectic) order. Ignoring elastic anharmonicities, but keeping…

Soft Condensed Matter · Physics 2009-10-30 Leo Radzihovsky , John Toner

A high-resolution calorimetric study has been carried out on nano-colloidal dispersions of aerosils in the liquid crystal 4-\textit{n}-pentylphenylthiol-4'-\textit{n}-octyloxybenzoate ($\bar{8}$S5) as a function of aerosil concentration and…

Soft Condensed Matter · Physics 2009-11-11 A. Roshi , G. S. Iannacchione , P. S. Clegg , R. J. Birgeneau , M. E. Neubert

We report combined optical birefringence and neutron scattering measurements on the liquid crystal 12CB nanoconfined in mesoporous silicon layers. This liquid crystal exhibits strong nematic-smectic coupling responsible for a discontinuous…

Mesoscale and Nanoscale Physics · Physics 2010-05-04 Gilbert Chahine , Andriy V. Kityk , Klaus Knorr , Ronan Lefort , Mohammed Guendouz , Denis Morineau , Patrick Huber

Liquid crystal elastomers present a rich combination of effects associated with orientational symmetry breaking and the underlying rubber elasticity. In this work we focus on the effect of the network on the nematic--smectic-{\sl A}…

Condensed Matter · Physics 2009-10-28 Peter D. Olmsted , Eugene M. Terentjev

The liquid crystalline compound, forming the glass of the smectic C$_A$* phase, is investigated by the X-ray diffraction in the 18-298 K range. The characteristic distances within the smectic C$_A$* phase are determined. The electron…

We present a theory of the elasticity and fluctuations of the Smectic A and C phases in uniaxial, anisotropic disordered environments, e.g., stretched aerogel. We find that, bizarrely, the low-temperature, lower-symmetry Smectic $C$ phase…

Soft Condensed Matter · Physics 2013-05-29 Leiming Chen , John Toner

Previous theoretical studies of calamitic (i.e., rod-like) ionic liquid crystals (ILCs) based on an effective one-species model led to indications of a novel smectic-A phase with a layer spacing being much larger than the length of the…

Soft Condensed Matter · Physics 2021-02-03 Hendrik Bartsch , Markus Bier , S. Dietrich

An extension to a high-order model for the direct isotropic/smectic-A liquid crystalline phase transition was derived to take into account thermal effects including anisotropic thermal diffusion and latent heat of phase-ordering.…

Soft Condensed Matter · Physics 2009-09-29 Nasser Mohieddin Abukhdeir , Alejandro D. Rey

We study smectic liquid crystals in random environments, e.g., aerogel. A low temperature analysis reveals that even arbitrarily weak quenched disorder (i.e., arbitrarily low aerogel density) destroys translational (smectic) order. A…

Soft Condensed Matter · Physics 2009-10-31 Leo Radzihovsky , John Toner

We report on strong pretransitional effects across the isotropic liquid-plastic crystal melting temperature in linear and nonlinear dielectric response. Studies were carried out for cyclooctanol (C8H16O) in the unprecedented range of…

Soft Condensed Matter · Physics 2019-12-10 A. Drozd-Rzoska , S. Starzonek , S. J. Rzoska , J. Łoś , Z. Kutnjak , S. Kralj
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