X-ray scattering of nematic liquid crystal nanodispersion with negative dielectric anisotropy [Invited]

Lorenz, Alexander; Zimmermann, Natalie; Kumar, Satyendra; Evans, Dean R.; Cook, Gary; Martínez, Manuel Fernández; Kitzerow, Heinz‐S.

doi:10.1364/ao.52.0000e1

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…Experimental details of measurements performed at beamline ID02 of the European Synchrotron Radiation Facility (ESRF) are described in Refs. [23,24]. During these measurements, the sample temperature was changed continuously but slowly (1.0°C/min).…”

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confidence: 99%

Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

et al. 2014

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Stack, chimneylike, and threadlike assemblies have previously been proposed for the structure of disodium cromoglycate (DSCG) aggregates in aqueous solutions. The results of the synchrotron x-ray scattering investigations reported here reveal the formation of simple columnar assemblies with π-π stacking at a separation of 3.4 Å between the DSCG molecules. Lateral separation between the assemblies is concentration and temperature dependent, varying from ∼35 to 42 Å in the orientationally ordered nematic (N) phase and from 27 to 32 Å in the columnar or middle (M) phase having long range lateral positional order. The assemblies' length depends on concentration and consists of ∼23 molecules in the N phase, becoming three to ten times larger in the M phase. The scission energy is concentration dependent in the N phase with values ∼7.19 ± 0.14 k_{B}T (15 wt %), 2.73 ± 0.4 k_{B}T (20 wt %), and 3.05 ± 0.2 k_{B}T (25 wt %). Solutions of all concentrations undergo a spinodal decomposition at temperatures above ∼40 °C, resulting in DSCG-rich regions with the M phase and water-rich regions in the N and isotropic phases.

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Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

et al. 2014

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“…In order to obtain small (even in the nano-range) particles, these inorganic substances have been milled in the presence of heptane as an organic solvent and oleic acid as a surfactant. [38][39][40][41][42][43][44] Using an organic solvent is desirable to make use of the dispersions obtained and dope target samples such as LCs, polymers or other samples with small, surface functionalized particles. An organic solvent can be removed from these samples easily (without varying the chemical composition of the doped substances).…”

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confidence: 99%

Surface grafted agents with various molecular lengths and photochemically active benzophenone moieties

Nordendorf

Schafforz

Käkel

et al. 2020

Phys. Chem. Chem. Phys.

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“…From these dispersions, stressed BaTiO 3 nanoparticles, which possess permanent electric polarization, can be harvested [13]. Generally, doping of LCs with milled BaTiO 3 nanoparticles allows one to vary the structural properties of smectic LCs [14] and to enhance the performance of devices based on both the nematic LCs [15][16][17][18][19][20] and ferroelectric LCs [21].…”

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confidence: 99%

Bilayers in nanoparticle-doped polar mesogens

et al. 2013

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Structures of the mesophases of five members of the 4-n-alkyl-4'-cyanobiphenyl homologous series (4-n-butyl-4'-cyanobiphenyl to 4-n-octyl-4'-cyanobiphenyl) doped with milled BaTiO_{3} nanoparticles were investigated by x-ray scattering. Clear solutions of each of the 4-n-alkyl-4'-cyanobiphenyls were first prepared in n-heptane and then doped with an n-heptane/nanoparticle dispersion, which led to gelation. The nanogels were found to be one-dimensional, multilayered, smectic nanostructures in each case. Surprisingly, a characteristic layer spacing of 4.5 nm was observed in all five homologues. Synchrotron x-ray scattering study of the multilayer structures of doped 4-n-pentyl-4'-cyanobiphenyl and 4-n-octyl-4'-cyanobiphenyl revealed nine orders of the primary Bragg reflection which were used to calculate the electron density profiles of the multilayers by Fourier analysis. The multilayers were found to consist of molecular bilayers wherein the mesogens were arranged in a head-to-head assembly of the polar head groups. The alkyl tails of the mesogenic molecules were freely movable and the tail-to-tail assembly was stabilized by heptane. The dissolved nanoparticles clearly induced a new self-assembled nanostructure in which the rigid aromatic part, and not the overall length, of the molecules defined the layer spacing.

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X-ray scattering of nematic liquid crystal nanodispersion with negative dielectric anisotropy [Invited]

Cited by 11 publications

References 13 publications

Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

Surface grafted agents with various molecular lengths and photochemically active benzophenone moieties

Bilayers in nanoparticle-doped polar mesogens

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