scholarly journals Structural characteristics of the epitropic liquid-crystalline layer of oleic acid

2018 ◽  
Vol 0 (55) ◽  
pp. 37-44
Author(s):  
А. Yu. Popovskii ◽  
B. А. Altoiz ◽  
А. F. Butenko
Keyword(s):  
Oleic Acid ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Crystalline Layer

Use of light microscopy in the qualitative and quantitative study of liquid crystalline order

1992 ◽  
Vol 50 (1) ◽  
pp. 264-265
Author(s):  
Christopher Viney
Keyword(s):  
Light Microscopy ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Molecular Order ◽  
Liquid Crystalline Phases ◽  
Convenient Technique ◽  
Liquid Crystalline Materials ◽  
Transparent Windows

Light microscopy is a convenient technique for characterizing molecular order in fluid liquid crystalline materials. Microstructures can usually be observed under the actual conditions that promote the formation of liquid crystalline phases, whether or not a solvent is required, and at temperatures that can range from the boiling point of nitrogen to 600°C. It is relatively easy to produce specimens that are sufficiently thin and flat, simply by confining a droplet between glass cover slides. Specimens do not need to be conducting, and they do not have to be maintained in a vacuum. Drybox or other controlled environmental conditions can be maintained in a sealed chamber equipped with transparent windows; some heating/ freezing stages can be used for this purpose. It is relatively easy to construct a modified stage so that the generation and relaxation of global molecular order can be observed while specimens are being sheared, simulating flow conditions that exist during processing. Also, light only rarely affects the chemical composition or molecular weight distribution of the sample. Because little or no processing is required after collecting the sample, one can be confident that biologically derived materials will reveal many of their in vivo structural characteristics, even though microscopy is performed in vitro.

scholarly journals Comparison of the Dielectric Properties of Ecoflex® with L,D-Poly(Lactic Acid) or Polycaprolactone in the Presence of SWCN or 5CB

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1719
Author(s):  
Patryk Fryń ◽  
Sebastian Lalik ◽  
Natalia Górska ◽  
Agnieszka Iwan ◽  
Monika Marzec
Keyword(s):  
Oleic Acid ◽  
Dielectric Properties ◽  
Polymer Matrix ◽  
Liquid Crystalline ◽  
Weight Ratio ◽  
Poly Lactic Acid ◽  
Relaxation Processes ◽  
The Matrix ◽  
Walled Carbon Nanotubes ◽  
Hybrid Layers

The main goal of this paper was to study the dielectric properties of hybrid binary and ternary composites based on biodegradable polymer Ecoflex®, single walled carbon nanotubes (SWCN), and liquid crystalline 4′-pentyl-4-biphenylcarbonitrile (5CB) compound. The obtained results were compared with other created analogically to Ecoflex®, hybrid layers based on biodegradable polymers such as L,D-polylactide (L,D-PLA) and polycaprolactone (PCL). Frequency domain dielectric spectroscopy (FDDS) results were analyzed taking into consideration the amount of SWCN, frequency, and temperature. For pure Ecoflex®, two relaxation processes (α and β) were identified. It was shown that the SWCN admixture (in the weight ratio 10:0.01) did not change the properties of the Ecoflex® layer, while in the case of PCL and L,D-PLA, the layers became conductive. The dielectric constant increased with an increase in the content of SWCN in the Ecoflex® matrix and the conductive behavior was not visible, even for the greatest concentration (10:0.06 weight ratio). In the case of the Ecoflex® polymer matrix, the conduction relaxation process at a frequency ca. several kilohertz appeared and became stronger with an increase in the SWCN admixture in the matrix. Addition of oleic acid to the polymer matrix had a smaller effect on the increase in the dielectric response than the addition of liquid crystal 5CB. Fourier transform infrared (FTIR) results revealed that the molecular structure and chemical character of the Ecoflex® and PCL matrixes remained unchanged upon the addition of SWCN or 5CB in a weight ratio of 10:0.01 and 10:1, respectively, while molecular interactions appeared between L,D-PLA and 5CB. Moreover, adding oleic acid to pure Ecoflex® as well as the binary and ternary hybrid layers with SWCN and/or 5CB in a weight ratio of Ecoflex®:oleic acid equal to 10:0.3 did not have an influence on the chemical bonding of these materials.

scholarly journals An organic crystalline state in ageing atmospheric aerosol proxies: spatially resolved structural changes in levitated fatty acid particles

2021 ◽  
Author(s):  
Adam Milsom ◽  
Adam M. Squires ◽  
Jacob A. Boswell ◽  
Nicholas J. Terrill ◽  
Andrew D. Ward ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Air Quality ◽  
Liquid Crystalline ◽  
Structural Changes ◽  
Unsaturated Fatty Acids ◽  
Organic Aerosols ◽  
Cloud Formation ◽  
Phase Gradient ◽  
Spatially Resolved ◽  
Surface Active

Abstract. Organic aerosols are key components of the Earth’s atmospheric system. The phase state of organic aerosols is known to be a significant factor in determining aerosol reactivity, water uptake and atmospheric lifetime – with wide implications for cloud formation, climate, air quality and human health. Unsaturated fatty acids contribute to urban cooking emissions and sea spray aerosols. These compounds, exemplified by oleic acid and its sodium salt, are surface active and have been shown to self-assemble into a variety of liquid-crystalline phases upon addition of water. Here we observe a crystalline acid–soap complex in acoustically levitated oleic acid–sodium oleate particles. We developed a synchrotron-based simultaneous Small-Angle & Wide-Angle X-ray Scattering (SAXS/WAXS)/Raman microscopy system to probe physical and chemical changes in the proxy during exposure to humidity and the atmospheric oxidant ozone. We present a spatially resolved structural picture of a levitated particle during humidification, revealing a phase gradient consisting of a disordered liquid crystalline shell and crystalline core. Ozonolysis is significantly slower in the crystalline phase compared with the liquid phase and a significant portion (34 ± 8 %) of unreacted material remains after extensive oxidation. We present experimental evidence of inert surface layer formation during ozonolysis, taking advantage of spatially resolved simultaneous SAXS/WAXS experiments. These observations suggest atmospheric lifetimes of surface-active organic species in aerosols are highly phase dependent, potentially impacting on climate, urban air quality and long-range transport of pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs).

Passive laser Q-switching using a dye-doped liquid-crystalline layer near total internal reflection

2001 ◽  
Vol 196 (1-6) ◽  
pp. 269-280 ◽  
Author(s):  
S.V. Serak ◽  
H.J. Eichler ◽  
A.A. Kovalev ◽  
T.A. Davidovich
Keyword(s):  
Total Internal Reflection ◽  
Liquid Crystalline ◽  
Internal Reflection ◽  
Crystalline Layer ◽  
Q Switching

Surfaces of Semi-Fluorinated Block Copolymers Studied Using Nexafs

1998 ◽  
Vol 524 ◽  
Author(s):  
J. Genzer ◽  
J. E. Sivaniah ◽  
E. J. Kramer ◽  
J. Wang ◽  
H. Körner ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Diblock Copolymer ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Crystalline Layer ◽  
Surface Normal ◽  
Electron Yield ◽  
Surface Liquid ◽  
Average Angle

ABSTRACTThe molecular orientation within a surface liquid crystalline layer made up of semifluorinated side-groups [-CO-(CH2)x−x-(CF2)yF] (SF groups) attached to the isoprene block of a styrene-isoprene diblock copolymer was determined by analyzing the partial electron yield Cedge NEXAFS signal. The results show that in contrast to the bulk, where the SF groups lie parallel to the diblock copolymer lamellae and thus parallel to the surface, the surface SF groups make an average angle with the surface normal of between 29 and 46° depending on x and y.

Rheological properties and associated structural characteristics of some aromatic polycondensates including liquid-crystalline polyesters and cellulose derivatives (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2027-2049 ◽  
Author(s):  
J. L. White ◽  
L. Dong ◽  
P. Han ◽  
H. M. Laun
Keyword(s):  
Shear Flow ◽  
Rheological Properties ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Cellulose Derivatives ◽  
Extrudate Swell ◽  
Polymer Liquid Crystals ◽  
Uniaxial Orientation ◽  
Technical Report ◽  
Thermotropic Polymer

A comparative experimental study of shear-flow rheological properties of thermotropic polymer liquid crystals by eight different laboratories is described. The materials involved four different liquid-crystalline polyesters (LCPs), a glass- fiber-filled liquid-crystalline polyester,hydroxypropyl cellulose (HPC), and two non-liquid-crystalline high-temperature polymers, a poly(etheretherketone) (PEEK), and a polyarylate (PAR). Studies were made in both steady shear-flow and dynamic oscillatory experiments. The data from the various laboratories involved were compared. The level of agreement in the data was much less for most liquid-crystalline polymers than for similar isotropic melts. The Cox –Merz rule is valid for PEEK and PAR, but not for the LCPs and HPC. The occurrence of low levels of extrudate swell and high levels of uniaxial orientation in extrudates of the LCPs and HPC is described.

scholarly journals Formation of Self-Assembled Liquid Crystalline Nanoparticles and Absorption Enhancement of Ω-3s by Phospholipids and Oleic Acids

Pharmaceutics ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 68
Author(s):  
Sang-Won Jeon ◽  
Han-Sol Jin ◽  
Young-Joon Park
Keyword(s):  
Oleic Acid ◽  
Liquid Crystal ◽  
Oral Bioavailability ◽  
Liquid Crystalline ◽  
In Vitro Dissolution ◽  
Absorption Enhancement ◽  
Epa And Dha ◽  
Liquid Crystalline Nanoparticles ◽  
Self Assembled ◽  
The Impact

This study aimed to optimize and evaluate self-assembled liquid crystalline nanoparticles (SALCs) prepared from phospholipids and oleic acid for enhancing the absorption of ω-3s. We explored the structure and optimal formulation of SALCs, which are composed of ω-3 ethyl ester (ω-3 EE), phospholipids, and oleic acid, using a ternary diagram and evaluated the improvement in ω-3 dissolution, permeation, and oral bioavailability. The in vitro dissolution and pharmacokinetics of ω-3 SALCs were compared with those of Omacor soft capsules (as the reference). The shape of the liquid crystal was determined according to the composition of phospholipids, oleic acids, and ω-3s and was found to be in cubic, lamellar, and hexagonal forms. The dissolution rates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) obtained from ω-3 SALCs were 1.7 to 2.3-fold higher than those of the Omacor soft capsules. Furthermore, a pharmacokinetic study in male beagle dogs revealed that ω-3 SALCs increased the oral bioavailability of ω-3 EE by 2.5-fold for EPA and 3.1-fold for DHA compared with the reference. We found an optimal formulation that spontaneously forms liquid crystal-based nanoparticles, improving the bioavailability of EPA and DHA, not found in the existing literature. Our findings offer insight into the impact of nanoparticle phase on the oral delivery of oil-soluble drugs and provide a novel ω-3 EE formulation that improves the bioavailability of EPA and DHA.

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