scholarly journals Introduction to Colloidal and Microfluidic Nematic Microstructures

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 956
Author(s):  
Simon Čopar ◽  
Miha Ravnik ◽  
Slobodan Žumer
Keyword(s):  
Soft Matter ◽  
Liquid Crystalline ◽  
Colloidal Particles ◽  
Topological Defects ◽  
Crystalline Materials ◽  
Inherent Anisotropy ◽  
Metastable Structures ◽  
Liquid Crystalline Materials ◽  
Mesoscopic Theory

In this brief review, we give an introduction to selected colloidal and microfluidic nematic microstructures, as enabled by the inherent anisotropy and microscopic orientational ordering in complex liquid crystalline materials. We give a brief overview of the mesoscopic theory, for equilibrium and dynamics, of nematic fluids, that provides the framework for understanding, characterization, and even prediction of such microstructures, with particular comment also on the role of topology and topological defects. Three types of nematic microstructures are highlighted: stable or metastable structures in nematic colloids based on spherical colloidal particles, stationary nematic microfluidic structures, and ferromagnetic liquid crystal structures based on magnetic colloidal particles. Finally, this paper is in honor of Noel A. Clark, as one of the world pioneers that helped to shape this field of complex and functional soft matter, contributing at different levels to works of various groups worldwide, including ours.

scholarly journals The Role of Substitution in the Apex Position of the Bent-Core on Mesomorphic Properties of New Series of Liquid Crystalline Materials

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 735 ◽  
Author(s):  
Helena Skopalová ◽  
Petr Špaček ◽  
Václav Kozmík ◽  
Jiří Svoboda ◽  
Vladimíra Novotná ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Structural Parameters ◽  
Phase Identification ◽  
Crystalline Materials ◽  
X Ray ◽  
Alkyl Chains ◽  
Calorimetric Measurements ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

We present the synthesis and mesomorphic properties of the new series of bent-core liquid crystals based on 3-hydroxybenzoic acid bearing a lateral substituent in the apex position. Four different substituents of various sizes and electronic properties have been used. We have found that only compounds substituted with fluorine are mesogenic and exhibit one mesophase, whose type differs when prolonging the terminal alkyl chain. For homologues with shorter alkyl chains (octyl, decyl), a columnar B1-type of a mesophase was observed, while materials with longer terminal chains (dodecyl, tetradecyl) exhibited a switchable lamellar SmCAPA phase. Calorimetric measurements, texture observations under a polarizing microscope were performed and electro-optical properties studied. Additionally, dielectric measurements were realized to characterize the molecular dynamics in the SmCAPA phase. All mesogenic compounds were further studied by X-ray measurements to confirm phase identification and obtain more information about their structural parameters.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

Designing Chemically Selective Liquid Crystalline Materials that Respond to Oxidizing Gases

2021 ◽  
Author(s):  
Nanqi Bao ◽  
Jake Gold ◽  
Tibor Szilvasi ◽  
Huaizhe Yu ◽  
Robert Twieg ◽  
...  
Keyword(s):  
Computational Methods ◽  
First Principles ◽  
Liquid Crystalline ◽  
Soft Materials ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Chemically Selective ◽  
Kinetics Of

Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively...

Orthoconic antiferroelectric liquid crystalline materials

2005 ◽  
Vol 72 (9) ◽  
pp. 655
Author(s):  
K. Czuprynski ◽  
J. Gasowska ◽  
M. Tykarska ◽  
P. Kula ◽  
E. Sokól ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials
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