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.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

Synthesis of Dendrimers Liquid Crystalline Materials based on 1,3,5-triphenylbenzene

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Linh I Awad ◽  
Nasreen R Jber
Keyword(s):  
Differential Scanning Calorimeter ◽  
Liquid Crystalline ◽  
Spectroscopic Method ◽  
Optical Microscope ◽  
Crystalline Materials ◽  
Liquid Crystalline Phases ◽  
Ft Ir ◽  
Liquid Crystalline Materials ◽  
New Compounds ◽  
Liquid Crystalline Dendrimers

In this study, new compounds of discotic liquid crystalline dendrimers are prepared which is derived from 1,3,5-triphenylbenzene. The synthesis of these compounds shows the effect of dendrimer unit on the mesogenic properties. The structures of prepared compounds characterized by using spectroscopic method e.g. FT-IR and 1HNMR. The liquid crystalline phases of prepared compounds was identified by using the hot-stage polarizing optical microscope (POM) and differential scanning calorimeter (DSC).

scholarly journals Chiral Photoresponsive Liquid Crystalline Materials Derived from Cyanoazobenzene Central Core: Effect of UV Light Illumination on Mesomorphic Behavior

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1161
Author(s):  
Anna Poryvai ◽  
Alexej Bubnov ◽  
Michal Kohout
Keyword(s):  
Liquid Crystalline ◽  
Uv Light ◽  
Structural Type ◽  
Optical Microscope ◽  
Light Illumination ◽  
Aromatic System ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

One of the most frequently utilized liquid crystalline (LC) materials is a rod-like (calamitic) compound 4-cyano-4′-pentylbiphenyl (5-CB). The main objective of this work is to enhance its functionality by introducing a photoresponsive diazenyl spacer in the aromatic core and replace the non-chiral pentyl chain with various chiral alkyl carboxylate units. The mesomorphic properties of the prepared materials have been studied using polarizing optical microscopy and differential scanning calorimetry. It has been found that materials with an extended aromatic system possess the liquid crystalline behavior. The studied LC materials have shown mesophases at lower temperatures than previously reported analogous substances. Furthermore, one of them exhibits a chiral orthogonal frustrated twist grain boundary smectic phase, which has not been previously observed for this structural type of materials. We also investigated photoresponse of the mesophases under illumination with UV-light (365 nm) using a polarizing optical microscope. A non-conventional photoresponse of the prepared materials in a crystalline phase is presented and discussed.

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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