Liquid crystals from shape-persistent porphyrin stars with intrinsic free space

2020 ◽  
Vol 8 (16) ◽  
pp. 5562-5571 ◽  
Author(s):  
Tapas Ghosh ◽  
Lisa Gerbig ◽  
Martin Lambov ◽  
Moritz Dechant ◽  
Matthias Lehmann
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Free Space ◽  
Oriented Films ◽  
Crystal Phases ◽  
Soft Crystal

Shape-persistent porphyrin star mesogens form thin oriented films of columnar liquid crystal and soft crystal phases as a function of the conjugated arm scaffold.

scholarly journals Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120263 ◽  
Author(s):  
H. N. W. Lekkerkerker ◽  
G. J. Vroege
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Colloidal Suspensions ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Future Developments ◽  
Mineral Particles ◽  
Crystal Phases ◽  
Liquid Crystal Phases

A review is given of the field of mineral colloidal liquid crystals : liquid crystal phases formed by individual mineral particles within colloidal suspensions. Starting from their discovery in the 1920s, we discuss developments on the levels of both fundamentals and applications. We conclude by highlighting some promising results from recent years, which may point the way towards future developments.

Pattern Formation During the Growth of Liquid Crystal Phases

MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Patrick Oswald ◽  
John Bechhoefer ◽  
Francisco Melo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Unit Vector ◽  
The Other ◽  
Two Dimensional ◽  
Smectic A ◽  
Anisotropic Plastic ◽  
Fundamental Research ◽  
Crystal Phases ◽  
Columnar Mesophases

Liquid crystals, discovered just a century ago, have wide application to electrooptic displays and thermography. Their physical properties have also made them fascinating materials for more fundamental research.The name “liquid crystals” is actually a misnomer for what are more properly termed “mesophases,” that is, phases having symmetries intermediate between ordinary solids and liquids. There are three major classes of liquid crystals: nematics, smectics, and columnar mesophases. In nematics, although there is no correlation between positions of the rodlike molecules, the molecules tend to lie parallel along a common axis, labeled by a unit vector (or director) n. Smectics are more ordered. The molecules are also rodlike and are in layers. Different subtypes of smectics (labeled, for historical reasons, smectic A, smectic B,…) have layers that are more or less organized. In the smectic A phase, the layers are fluid and can glide easily over each other. In the smectic B phase, the layers have hexagonal ordering and strong interlayer corrélations. Indeed, the smectic B phase is more a highly anisotropic plastic crystal than it is a liquid crystal. Finally, columnar mesophases are obtained with disklike molecules. These molecules can stack up in columns which are themselves organized in a two-dimensional array. There is no positional correlation between molecules in one column and molecules in the other columns.

scholarly journals Liquid Crystals Templating

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 648 ◽  
Author(s):  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Inorganic Materials ◽  
The Self ◽  
Thermotropic Liquid Crystals ◽  
Versatile Technique ◽  
Crystal Phases ◽  
Nanoscale Features ◽  
Mesoporous Membranes ◽  
Liquid Crystal Templating

Liquid crystal templating is a versatile technique to create novel organic and inorganic materials with nanoscale features. It exploits the self-assembled architectures of liquid crystal phases as scaffolds. This article focuses on some of the key developments in lyotropic and thermotropic liquid crystals templating. The procedures that were employed to create templated structures and the applications of these novel materials in various fields including mesoporous membranes, organic electronics, the synthesis of nanostructured materials and photonics, are described.

scholarly journals Adjacent functional group effects on the assembly of columnar liquid crystals

2020 ◽  
Vol 98 (7) ◽  
pp. 379-385
Author(s):  
Carson O. Zellman ◽  
Danielle Vu ◽  
Vance E. Williams
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Self Assembly ◽  
Room Temperature ◽  
Functional Group ◽  
The Self ◽  
Clearing Temperature ◽  
Crystal Phases ◽  
Potential Strategy ◽  
The Impact

Although the impact of individual functional groups on the self-assembly of columnar liquid crystal phases has been widely studied, the effect of varying multiple substituents has received much less attention. Herein, we report a series of dibenzo[a,c]phenazines containing an alcohol or ether adjacent to an electron-withdrawing ester or acid. With one exception, these difunctional mesogens form columnar phases. The phase behavior appeared to be dominated by the electron-withdrawing substituent; transition temperatures were similar to derivatives with these groups in isolation. In most instances, the addition of an electron-donating group ortho to an ester or acid suppressed the melting temperature and elevated the clearing temperature, leading to broader liquid crystal thermal ranges. This effect was more pronounced for derivatives functionalized with longer chain hexyloxy groups. These results suggest a potential strategy for controlling the phase ranges of columnar liquid crystals and achieving room temperature mesophases.

The chemistry of liquid crystals

1983 ◽  
Vol 309 (1507) ◽  
pp. 77-92 ◽  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Physical Characteristics ◽  
Structure Property ◽  
Theoretical Concepts ◽  
Crystal State ◽  
Qualitative Understanding ◽  
Fluid Systems ◽  
Crystal Phases ◽  
Liquid Crystal Phases

The nature of the liquid crystal phases formed by different compounds and the thermal and other physical characteristics of these phases are strongly affected by the stereochemistry and structure of the molecules. Precise structure-property correlations of an embracing nature cannot yet be quantified, but even a qualitative understanding of such relations is desirable from many standpoints, including that of the achievement of still better liquid crystal materials for the ever widening range of applications that is emerging for these ordered but fluid systems. By means of a range of selected examples, an attempt is made to illustrate not only those areas where generalizations seem possible, but also others wherein the properties of the materials are much more difficult to understand, to such an extent that doubt must be cast on at least some theoretical concepts of the liquid crystal state.

Liquid Crystals in Ternary Polyoxyethylene Trisiloxane Surfactant - Silicone Oil - H2O System

1996 ◽  
Vol 425 ◽  
Author(s):  
X. Li ◽  
R. M. Hill ◽  
L. E. Scriven ◽  
H. T. Davis
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Small Angle ◽  
Silicone Oil ◽  
Head Group ◽  
X Ray ◽  
X Ray Scattering ◽  
Crystal Phases ◽  
Liquid Crystal Phases ◽  
Ray Scattering

AbstractPolyethylene trisiloxane surfactants M(D′En)M (n=6, 8, 10, 12) self assemble into sheet-like structure and form various lyotropic cubic, hexagonal and lamellar liquid crystal phases in ternary trisiloxane surfactant - silicone oil - water systems. Small angle X-ray scattering (SAXS) was used to identify and characterize the liquid crystal phases. Cyclic octamethylcyclotetrasiloxane (D4), decamethyl-cyclopentasiloxane(D5) and short linear decamethyltetrasiloxane (MD2M) silicone oils facilitate the formation of liquid crystals. The structures in liquid crystals (LC) progress from zero curvature lamellar liquid crystals to higher curvature cubic liquid crystals with increasing the surfactant hydrophilic head group size. The effects of surfactant and oil concentration on the lamellar bilayer thickness and molecular packing were studied with small angle X-ray scattering.

ON CONSTRUCTION OF POISSON BRACKETS AND DYNAMICS OF LIQUID CRYSTALS

1994 ◽  
Vol 08 (11) ◽  
pp. 677-686 ◽  
Author(s):  
A. A. ISAYEV ◽  
M. Yu. KOVALEVSKY ◽  
S. V. PELETMINSKY
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Poisson Brackets ◽  
Hamiltonian Approach ◽  
General Algebra ◽  
Crystal Phases ◽  
Dynamic Variables ◽  
Liquid Crystal Phases

Dynamics of classical continuum and of some liquid crystal phases are considered in the Hamiltonian approach. Poisson brackets for variables of liquid crystals are obtained as subalgebras of the general algebra of continuum dynamic variables.

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