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Artículos de revistas sobre el tema "Mesogenic systems"

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Publicado: 18 de mayo de 2024

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1

Chao, C. Y., X. Li y C. K. Ober. "Directing self-assembly in macromolecular systems: Hydrogen bonding in ordered polymers". Pure and Applied Chemistry 76, n.º 7-8 (1 de enero de 2004): 1337–43. http://dx.doi.org/10.1351/pac200476071337.

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Hydrogen-bonded side-chain liquid-crystalline block copolymers (SCLCBCPs) containing block segments with proton donors were combined with functionalized mesogenic pendent groups. Studies of a wide range of mesogen and polymer combinations were carried out to study the relationship between morphology and mesophase behavior. The thermal behaviors of the resulting self-assembled microstructures were also examined. A model of the assembly process leading to mesogenic group organization corresponding to different compositions was proposed.
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2

Vora, R. A. y S. J. Rajput. "Binary Mesogenic Systems Comprised of Ester Mesogens and Non-Mesogens". Molecular Crystals and Liquid Crystals 209, n.º 1 (diciembre de 1991): 265–77. http://dx.doi.org/10.1080/00268949108036201.

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3

Koßmehl, Gerhard y Jürgen Bahr. "Liquid Crystalline Azomethines and Polyazomethines Containing Azobenzene and Stilbene Units". Zeitschrift für Naturforschung B 46, n.º 2 (1 de febrero de 1991): 245–54. http://dx.doi.org/10.1515/znb-1991-0219.

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Azobenzene and stilbene derivatives with azomethine and ester groups and polymers of corresponding structures with mesogens possessing three to four aromatic systems in their mesogenic units have been synthesized, characterized and studied for their liquid crystalline properties by DSC measurements and observation by polarizing microscopy.
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4

Mirnaya, T. A., G. G. Yaremchuk y S. V. Volkov. "Phase Diagrams of Binary Alkanoate Systems with Common Cation: Potassium Isobutyrate-Propionate, and Sodium Butyrate-Isobutyrate". Zeitschrift für Naturforschung A 51, n.º 8 (1 de agosto de 1996): 957–59. http://dx.doi.org/10.1515/zna-1996-0811.

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Abstract The phase diagrams of the binary mixtures of mesogenic potassium isobutyrate with non-mesogenic potassium propionate and mesogenic sodium butyrate with non-mesogenic sodium isobutyrate have been investigated by differential thermal analysis and hot stage polarization microscopy. Both systems have one eutectic and one metatectic phase equilibriums. Pecularities of liquid crystal formation in binary alkanoate systems with common alkali metal cation are discussed and compared with those of systems with common anion.
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5

Dolden, J. G. y P. T. Alder. "The Mesogenic Index: An Empirical Method for Predicting Polymeric Liquid Crystallinity". High Performance Polymers 10, n.º 3 (septiembre de 1998): 249–72. http://dx.doi.org/10.1088/0954-0083/10/3/004.

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An empirical method for predicting the chemical compositions of random or partially ordered copolymers that exhibit mesophases was devised by the authors in 1989, while working on liquid crystal copolymer synthesis for BP Chemicals. A brief description of the method and its application to the chemical synthesis of amorphous thermotropic polyamides was given by the authors in a previous paper. Thermotropic polyimides were also synthesized by the authors as a result of the use of the predictive method. Subsequently, the method has been updated and applied to polycarbonates and polyimides. The new approach has been termed ‘the mesogenic index’ (MI) and has successfully been applied to 23 copolymer systems in which the critical compositions for mesophase formation have been established by means of varying constituent monomer concentrations. It is also consistent in predicting liquid crystalline behaviour in several hundred main-chain polymer systems containing amide, ester, carbonate, ether and urethane groups. It is inherent in the MI system that the mesogenic length is defined in terms of the number of monomer units for a given polymer class. From published work in the literature, it was first established that ester and amide groups need at least two and three aromatic rings in the mesogen respectively. Using these values to define mesogen length in polyester and polyamide copolymers, the condition MI > 10 has been determined for mesophase formation. This rule has been applied to other linking groups, such as carbonate or imide, with the surprising result that the corresponding mesogen lengths for these condensation polymers are simple numbers. Moreover, the rule has been applied successfully to mixed systems, by simply averaging the contributions of the different groups to the mesogen length in strictly molar proportions. The mesogenic index is based upon summing functional group contributions towards rigidity and/or resonance stabilization of the mesogen. To the best of our knowledge, this is the first simple method to be published that successfully correlates chemical composition with mesophase formation.
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6

Mirnaya, T. A., G. G. Yaremchuk y S. V. Volkov. "Phase Diagrams of Binary Systems of Some Alkali Iso–Butyrates with One Mesogenic Component". Zeitschrift für Naturforschung A 50, n.º 9 (1 de septiembre de 1995): 893–96. http://dx.doi.org/10.1515/zna-1995-0917.

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Abstract The phase diagrams of the binary mixtures of mesogenic potassium iso-butyrate with non-mesogenic lithium-, sodium-, and caesium iso-butyrate have been investigated by differential thermal analysis and hot stage polarization microscopy. The temperature and concentration ranges of liquid crystal formation have been established. Sodium and caesium iso-butyrate have been found to possess latent mesogenic properties.
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7

Mirnaya, T. A., Y. V. Bereznitski y S. V. Volkov. "Liquid Crystals and Glasses in Binary Systems from Sodium and Alkali-Earth Metal Butyrates". Zeitschrift für Naturforschung A 51, n.º 7 (1 de julio de 1996): 867–70. http://dx.doi.org/10.1515/zna-1996-0711.

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Abstract The temperature and composition ranges of liquid crystal and glass formation have been established for the binary mixtures of mesogenic sodium butyrate with non-mesogenic magnesium, calcium and strontium butyrates by means of differential thermal analysis and hot stage polarization microscopy. The formation of a vitreous optically anisotropic mesophase has been found for binaries of sodium butyrate with calcium and strontium butyrates.
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8

Krigbaum, William R. "Phase studies of binary mesogenic systems". Faraday Discussions of the Chemical Society 79 (1985): 133. http://dx.doi.org/10.1039/dc9857900133.

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9

Bubnov, Alexej, Martin Cigl, Deyvid Penkov, Marek Otruba, Damian Pociecha, Hsiu-Hui Chen y Věra Hamplová. "Design and Self-Assembling Behaviour of Calamitic Reactive Mesogens with Lateral Methyl and Methoxy Substituents and Vinyl Terminal Group". Polymers 13, n.º 13 (30 de junio de 2021): 2156. http://dx.doi.org/10.3390/polym13132156.

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Smart self-organising systems attract considerable attention in the scientific community. In order to control and stabilise the liquid crystalline behaviour, and hence the self-organisation, the polymerisation process can be effectively used. Mesogenic units incorporated into the backbones as functional side chains of weakly cross-linked macromolecules can become orientationally ordered. Several new calamitic reactive mesogens possessing the vinyl terminal group with varying flexible chain lengths and with/without lateral substitution by the methyl (methoxy) groups have been designed and studied. Depending on the molecular structure, namely, the type and position of the lateral substituents, the resulting materials form the nematic, the orthogonal SmA and the tilted SmC phases in a reasonably broad temperature range, and the structure of the mesophases was confirmed by X-ray diffraction experiments. The main objective of this work is to contribute to better understanding of the molecular structure–mesomorphic property relationship for new functional reactive mesogens, aiming at further design of smart self-assembling macromolecular materials for novel sensor systems.
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10

Li, Qian Yue, Jun Xu, Wen Zheng Zhang y Peng Li. "Preparation and Characterization of Chiral Cyclosiloxane-Based Liquid-Crystalline Elastomers Bearing Menthyl Groups". Advanced Materials Research 466-467 (febrero de 2012): 445–48. http://dx.doi.org/10.4028/www.scientific.net/amr.466-467.445.

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Chiral side-chain liquid-crystalline elastomers (LCEs) IP~IVP containig menthyl groups were synthesized by a one-step hydrosilylation reaction. The chemical structures and LC properties of the monomers and polymers were characterized by use of various experimental techniques. The effect of crosslinking mesogens on mesomorphic properties of the chiral LCEs was studied by swelling experiments. All the samples IP~IVP showed cholesteric mesophase when they were heated and cooled, proved by visual observation and X-ray measurements. The glass transition temperature (Tg) of elastomers increased slightly with increase of crosslinking mesogens in the polymer systems, but mesophase-isotropic phase transition temperature (Ti) decreased slightly, suggesting that the temperature range of mesophase became narrow with increase of crosslinking mesogens for all the elastomers. The maximum reflection bands shift slightly to long wavelength and become broad at the same temperature, indicating that the helical structure is partially disrupted because of both the constraint of chemical crosslinking agents and the different mesogenic units.
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11

Hakemi, H. "The effect of a compatible liquid crystal polymer on homogeneous reinforcement of mesogenic and nonmesogenic rigid-rod monomers". Material Science & Engineering International Journal 6, n.º 1 (31 de enero de 2022): 1–4. http://dx.doi.org/10.15406/mseij.2022.06.00172.

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Discrete amount of main-chain Liquid Crystal Polymers (LCP) could mechanically reinforce the mesophase of rigid-rod monomers to form a supramolecular homogeneous composite for Liquid Crystal Display (LCD) materials. Moreover, a homogeneously dispersed LCP may induce an enantiotropic transition in monotropic or non-mesogenic rigid-rod compounds. In this work, we studied the blends of a flexible main-chain nematic LCP with an enantiotropic nematic, a monotropic nematic, and two non-mesogenic rigid-rod compounds as model systems. The results indicate that homogenous reinforcement of thermotropic LCP in these monomers is a valid concept and could lead to improvement of mesogenic stability, orienational and mechanical properties of rigid-rod materials for various applications.
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12

Usol’tseva, Nadezhda V. y Antonina I. Smirnova. "Liquid Crystals as Lubricants". Lubricants 7, n.º 12 (9 de diciembre de 2019): 111. http://dx.doi.org/10.3390/lubricants7120111.

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The review summarizes the literature data and the authors’ own research results on the application of liquid crystals in tribology. It has been shown that both thermotropic (calamitic, discotic, cholesteric) and lyotropic (surfactants, chromonics) mesogens as tribological additives are able to optimize the properties of lubricating compositions when introduced even at low concentrations to oils and greases. A wide possibility of varying the chemical structure of mesogens and studying the relationship between their structure and tribological properties can be used for the desired (programmed) change of the quality of tribotechnical processes. The synergism of the combined use of mesogenic esters of cholesterol and carbon nanostructures as additives in improving tribological properties has been established. The use of synthetic lubricants in biological systems still requires further research as the experimental results obtained on models of joint prostheses in vitro conditions are significantly worse than the results obtained in vivo. Considering the annual loss of billions of US dollars worldwide due to the low efficiency of friction processes in the industry and the resulting wear, liquid crystals and the systems based on them can be the most effective way to optimize these processes. The present review will be useful for researchers and industrialists.
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13

Wilson, Mark R. y David A. Dunmur. "Light-scattering studies of molecular association in mesogenic systems". Journal of the Chemical Society, Faraday Transactions 86, n.º 7 (1990): 1113. http://dx.doi.org/10.1039/ft9908601113.

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14

Sastry, S. Sreehari y Kothapalli Vijaya Lakshmi. "Inducement of smectic phases in hydrogen-bonded mesogenic systems". Liquid Crystals 38, n.º 4 (15 de abril de 2011): 483–88. http://dx.doi.org/10.1080/02678292.2011.552743.

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15

Toriyama, K. y D. A. Dunmur. "A new model for dipole-dipole association in mesogenic systems". Molecular Physics 56, n.º 2 (10 de octubre de 1985): 479–84. http://dx.doi.org/10.1080/00268978500102461.

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16

Tsai, Yu-Tang, Chien-Yu Chen, Li-Yin Chen, Su-Hao Liu, Chung-Chih Wu, Yun Chi, Shaw H. Chen, Hsiu-Fu Hsu y Jey-Jau Lee. "Analyzing nanostructures in mesogenic host–guest systems for polarized phosphorescence". Organic Electronics 15, n.º 1 (enero de 2014): 311–21. http://dx.doi.org/10.1016/j.orgel.2013.11.025.

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17

Witko, Wacław y Renata Tokarz-Sobieraj. "Quantum Modeling of Geometric Electronic Structures of Some Mesogenic Systems". Molecular Crystals and Liquid Crystals 480, n.º 1 (29 de enero de 2008): 219–28. http://dx.doi.org/10.1080/15421400701826605.

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18

Amann, Tobias y Andreas Kailer. "Ultralow Friction of Mesogenic Fluid Mixtures in Tribological Reciprocating Systems". Tribology Letters 37, n.º 2 (6 de octubre de 2009): 343–52. http://dx.doi.org/10.1007/s11249-009-9527-2.

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19

Liu, Su-Hao, Ming-Shiang Lin, Li-Yin Chen, Yun-Hua Hong, Chih-Hung Tsai, Chung-Chih Wu, Anurach Poloek, Yun Chi, Chien-An Chen y Shaw H. Chen. "Polarized phosphorescent organic light-emitting devices adopting mesogenic host–guest systems". Organic Electronics 12, n.º 1 (enero de 2011): 15–21. http://dx.doi.org/10.1016/j.orgel.2010.09.020.

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20

Yurasova, T. A. y A. N. Semenov. "Nematic Phase Transition in Systems of Polymer Chains with Mesogenic Groups". Molecular Crystals and Liquid Crystals 199, n.º 1 (mayo de 1991): 301–8. http://dx.doi.org/10.1080/00268949108030941.

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21

Koßmehl, Gerhard y Frank Dirk Hoppe. "Liquid Crystalline Compounds in the Thiophene Series, Part 7+". Zeitschrift für Naturforschung B 48, n.º 12 (1 de diciembre de 1993): 1807–20. http://dx.doi.org/10.1515/znb-1993-1218.

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Compounds with two mesogenic groups without terminal alkyl chains or other groups containing thiophene systems have been prepared from α.ω-bis(5-formyl-2-thienyl)alkanes (series 1) and various phosphonium salts by Wittig-reaction. The chemical structures of the new compounds have been characterized by their elemental analyses, IR and 1H NMR spectra and MS. The liquid crystalline properties of these compounds were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Mesogenic cores with one thiophene system and two benzene systems give rise to liquid crystalline phases. These compounds with one vinylene group in each core (series 2 and 3) are mostly monotropic, those with two or three vinylene groups are enantiotropic liquid crystalline. Exchanging one vinylene group by a azomethine group in each core reduces the temperature range of the mesophase or destroys the liquid crystallinity completely. In contrast to E,E-1-(5-butyl-2-thienylvinyl)-4-(styryl)benzene (9) with no mesophase the corresponding all-E-α.ω-bis{5-[4-(4-styryl)styryl]-2-thienyl}alkanes (series 5) show over a wide temperature range with increasing inner chain length more and more high ordered mesophases. all-E-α.ω-Bis{5-[4-(4-phenylbuta-1.3-dienyl)styryl]-2-thienyl}alkanes (series 7) decompose in their mesophases.
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22

Prabu, N. Pongali Sathya, V. N. Vijayakumar y M. L. N. Madhu Mohan. "Influence of Terminal Groups on the Mesogenic Properties of Self-Assembly Systems". Molecular Crystals and Liquid Crystals 548, n.º 1 (7 de octubre de 2011): 142–54. http://dx.doi.org/10.1080/15421406.2011.591682.

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23

Singh. "Impact of Dispersion of Nanoscale Particles on the Properties of Nematic Liquid Crystals". Crystals 9, n.º 9 (11 de septiembre de 2019): 475. http://dx.doi.org/10.3390/cryst9090475.

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This work reviews the recent progress made in last decade in understanding the role of dispersion ofnanoparticles and quantum dots into host nematic liquid crystals. There are two important ingredients of this work: Even a minute concentration of these non-mesogenic materials in host matrix can have reflective impact on the dielectric, electro-optical, and spectroscopic properties of host nematics and the nematic-nanoparticles composite systems become suitable for the use in nematic based display and other devices.
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24

Lebedev, Ivan S., Ivan A. Filippov, Kseniya E. Bubnova, Nina I. Giricheva, Mikhail S. Fedorov y Svetlana A. Syrbu. "STUDY OF STRUCTURAL ORGANIZATION OF SYSTEMS ON BASIS OF p-n-PROPYLOXICINNAMIC ACID AND NONMESOGENES OF Ph–X–Ph TYPE". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, n.º 4 (7 de abril de 2019): 87–94. http://dx.doi.org/10.6060/ivkkt.20196204.5973i.

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The variants of structural organization in the systems “mesogen – nonmesogen” are considered. The systems contain p-n-propyloxycinnamic acid (A), as a mesogenic component, and nonmesogenic Ph–X–Ph compounds: phenyl benzoate (B, where X = –COO–), azobenzene (C, where X = –N=N–) and N-benzylideneaniline (D, where X = –CH=N–). Quantum-chemical modeling of possible structural units in such systems has been performed. It was shown that all assumed A∙∙∙X(Ph)2 H-complexes do not have electronic and geometric anisotropy and have a lower intermolecular interaction energy than the cyclic dimer of acid A∙∙∙A. The calculated values of the Gibbs free energy of complexation reactions also indicate a low probability of the formation of A∙∙∙X(Ph)2 type H-complexes. It is noted that the “length” of the A∙∙∙A dimer is comparable with the doubled “length” of Ph–X–Ph molecules, which, like the acid dimer, have a rod-like structure favorable for the formation of nematic and smectic LC phases. Based on the analysis of the quantum chemical calculations, it was assumed that Ph–X–Ph can be embedded between acid cyclic dimers A∙∙∙A and can facilitate reduce intermolecular interactions in the system, which reduces the temperature of Cr–LC transitions. The proposed structural organization of systems A: Ph–X–Ph is confirmed by an experimental IR spectrum for a similar system, in which the bands corresponding to the vibrational frequencies of the acid dimer and to individual molecules of alkyloxy substituted phenyl benzoate B are recorded.
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25

Shabatina, Tatyana I. y Yurii N. Morosov. "Hybrid Nanosystems Based on Metal-Containing Mesogenic CyanoAlkyl and Alkoxybiphenyls". Crystals 10, n.º 2 (30 de enero de 2020): 77. http://dx.doi.org/10.3390/cryst10020077.

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The paper reviews the results of the authors on the production of hybrid nanosystems based on liquid crystalline (LC) long-chain cyano(alkyl and alkoxy)biphenyls (5CB, 5OCB, and 8CCB) including nanosized metal species. The samples were obtained through the direct incorporation of metal (silver and copper) atoms and small clusters into mesogenic CB matrices via a low temperature co-condensation technique, and the formation of biligand metal complexes were revealed by FTIR and ESR-spectroscopy. The heating of the systems led to the controlled growth of metal clusters and nanosized metal particles of the definite size beginning from 1 up to 200 nanometers, and their highly-ordered assemblies stabilized in the solid and liquid crystalline phases. It is shown that supramolecular ordering in different LC phases of cyanobiphenyl matrices determines the size and shape of nanosized metal species that are formed in the systems under investigation, as well as the morphology of their aggregates. TEM and atomic force microscopy (AFM) data revealed the existence of orientationally-ordered nanostructures in the nematic phases of 5CB and 5OCB. The growth of quasi-fractal 2D-aggregates was shown for layer-structured smectic mesophase of 8CB. The UV–Visible spectra of hybrid metal–mesogenic nanosystems Ag-5CB and Cu-5CB that were incorporated into polymeric films revealed intensive plasmonic bands at 400–450 nm, similar to silver nanoparticles, and 540–650 nm, similar to copper nanoparticles. The increasing of the metal contents in the samples caused the growth of highly anisometric shaped metal rods, with the ratio of the length to the diameter being more than 10 and plasmonic bands at region of λ ≥ 650 nm.
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26

Tokmenko, Inna I., Tatyana A. Mirnaya y Galina G. Yaremchuk. "Phase Diagrams of Mesogenic Binary Systems of Cobalt(II) and Univalent Metal Octanoates". Zeitschrift für Naturforschung A 66, n.º 10-11 (1 de noviembre de 2011): 661–67. http://dx.doi.org/10.5560/zna.2011-0031.

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The phase diagrams of binary systems of cobalt(II) octanoate and lithium, sodium, potassium, and thallium(I) octanoates have been studied by differential thermal analysis and polythermal polarization microscopy. In all systems, continuous or limited liquid crystalline solutions of smectic modification are formed. The temperature and composition ranges of the formation of liquid crystals and glasses have been determined.
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27

Escobedo, Fernando A. y Juan J. de Pablo. "Monte Carlo simulation of athermal mesogenic chains: Pure systems, mixtures, and constrained environments". Journal of Chemical Physics 106, n.º 23 (15 de junio de 1997): 9858–68. http://dx.doi.org/10.1063/1.473874.

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28

Ujiie, Seiji, Shunsuke Takagi y Moriyuki Sato. "Lamellar Mesophases Formed by Thermotropic Liquid Crystalline Ionic Polymer Systems without Mesogenic Units". High Performance Polymers 10, n.º 1 (marzo de 1998): 139–46. http://dx.doi.org/10.1088/0954-0083/10/1/015.

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Mixtures consisting of polyamine (branched polyethyleneimine (PEI) and polyallylamine (PAA)) and n-alkanoic acid (C n: n = the carbon number of alkanoic acid) were prepared and their thermal and liquid crystalline properties were examined. The occurrence of proton transfer from the carboxylic acid to the amine groups was found by IR measurement of the mixtures. The polyamines and C n exhibited no mesophase. Also, PEI/C n with n = 3, 4, 5, which are mixtures of PEI and C n, did not show a liquid crystalline phase. However, PEI/C n with n> 5 clearly displayed a lamellar fluid liquid crystal phase having a layer structure with low order inside the layer, due to ion–ion interactions. In the lamellar mesophase, PEI/C n showed a focal-conic fan texture which resembles the fan-shaped textures in smectic A and C phases. PEI/C n with 5 < n < 13 formed a bilayer structure in the lamellar mesophase. On the other hand, a tilted bilayer structure is proposed as a packing model of PEI/C n with 13 < n< 19. PAA/C18 consisting of polyallylamine and C18 also showed a lamellar fluid mesophase and formed a similar layer structure to PEI/C18.
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29

Bhatt, Himanshu S., Purvang D. Patel y Jayrang S. Dave. "Study of Mixed Mesomorphism in Binary Systems of Azo-Ester Mesogens With Structurally Dissimilar Nonmesogenic As Well As Mesogenic Ester Homologues". Molecular Crystals and Liquid Crystals 587, n.º 1 (enero de 2013): 80–91. http://dx.doi.org/10.1080/15421406.2013.807708.

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30

Wang, Meng, Xu Pan, Shangfeng Xiao, Changneng Zhang, Wenxin Li y Songyuan Dai. "Regulating mesogenic properties of ionic liquid crystals by preparing binary or multi-component systems". J. Mater. Chem. 22, n.º 5 (2012): 2299–305. http://dx.doi.org/10.1039/c1jm14790k.

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31

Socaciu, Margareta, Carmina Plosceanu, Iuliana Cuculescu y I. Muşcutariu. "Determination of phase transitions in binary systems of mesogenic compounds by optical absorption spectroscopy". Phase Transitions 6, n.º 4 (marzo de 1986): 249–57. http://dx.doi.org/10.1080/01411598608220069.

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32

Rogozhin, V. B., S. G. Polushin, A. A. Lezova, G. E. Polushina y A. S. Polushin. "Simulation of Structural Transition in an Isotropic Melt of Nematic and Smectic Polymers". WSEAS TRANSACTIONS ON SYSTEMS 23 (15 de febrero de 2024): 105–12. http://dx.doi.org/10.37394/23202.2024.23.12.

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The isotropic phases of four fractions of a mesogenic comb-shaped polymer were studied using the electric birefringence method. The fractions have either nematic – isotropic melt, or smectic-A – isotropic melt phase transition, depending on the degree of polymerization. All samples showed a structural transition in isotropic phase. Mathematical modeling of the electro-optical properties was performed based on the modified Landau-De Gennes theory using three- order parameters. The reason for the transition in the isotropic phase is the mutual rearrangement of the polar side groups of the polymer as a result of dipole-dipole interaction.
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33

Ban, Jian Feng, Shao Rong Lu, Dong Guo, Kuo Liu y Chong Xi Luo. "Thermomechanical Properties and Morphology of Liquid Crystalline Polyurethane/Epoxy Resin Composites". Advanced Materials Research 194-196 (febrero de 2011): 1421–25. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1421.

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One new kind of epoxy resin toughening agent defined as liquid crystalline polyurethane elastomers (LCPUE) containing mesogenic ester groups and trithylene glycol flexible chain was synthesized and its nematic structure was observed by POM and XRD. The LCPUE was to modify the epoxy resin (E-51). The mechanical properties, fracture surface morphology, and thermal properties of the E-51/LCPUE curing system were systematically investigated. Experimental results revealed that the impact strength of the epoxy resin modified with LCPU is 1.9 times higher than that of the unmodified system, enhanced the thermal decomposition temperature by about 12 °C, and the fracture surfaces all modified systems display tough fracture feature.
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34

Mirnaya, T. A., G. G. Yaremchuck y S. V. Volkov. "Phase Diagrams of Binary Systems of Non-Mesogenic Components:Caesium-Sodium and Caesium—Lithium Iso-Butyrates". Zeitschrift für Naturforschung A 50, n.º 10 (1 de octubre de 1995): 965–68. http://dx.doi.org/10.1515/zna-1995-1011.

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Abstract The phase diagrams of the binary systems given in the title have been studied by differential thermal analyses and hot stage polarization microscopy. Smectic liquid crystals are found in some composition ranges of the binary with sodium iso-butyrate. The liquid crystal appearance in this system is explained by latent mesomorphism of both components and by the additional electrostatic stabilization of the ionic mesophase because of dissimilar cation interactions. The unlike conditions for the exhibition of latent mesomorphism of caesium isobutyrate in the two systems is discussed.
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35

Varga, Szabolcs y Franz J. Vesely. "A new generic model potential for mesogenic systems: Square well line potential of variable range". Journal of Chemical Physics 131, n.º 19 (2009): 194506. http://dx.doi.org/10.1063/1.3264109.

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36

Lei, Zih-Yang, Gene-Hsiang Lee y Chung K. Lai. "Luminescent mesogenic borondifluoride complexes with the Schiff bases containing salicylideneamines and β-enaminoketones core systems". Journal of Molecular Liquids 260 (junio de 2018): 44–56. http://dx.doi.org/10.1016/j.molliq.2018.03.047.

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37

Prajapati, A. K. y Himanshu M. Pandya. "Exhibition of Induced Mesophases in the Binary Systems Where Both the Components are Non-Mesogenic". Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 365, n.º 1 (1 de julio de 2001): 43–54. http://dx.doi.org/10.1080/10587250108025280.

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38

Ahmed, Hoda A. y Muna S. Khushaim. "Nematic Phase Induced from Symmetrical Supramolecular H-Bonded Systems Based on Flexible Acid Core". Crystals 10, n.º 9 (10 de septiembre de 2020): 801. http://dx.doi.org/10.3390/cryst10090801.

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New symmetrical 1:2 supramolecular H-bonded liquid crystals (SMHBLCs) interactions, A/2Bn, were formed between adipic acid and 4-(4′–pyridylazophenyl) 4″-alkoxybenzoates. Optical and mesomorphic behaviors of the prepared SMHBLC complexes were investigated using differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD). FT-IR spectroscopy was carried out to confirm the H-bond interactions of the prepared complexes via Fermi bands formation. Their photo-physical properties were investigated by UV-spectroscopy and the observed absorbance values were found to be mainly dependent on the length of the terminal alkoxy chain. Mesomorphic behaviour for all A/2Bn complexes revealed that all complexes are dimorphic-exhibiting enantiotropic mesophases with induced nematic phases, except for the long chain terminal complex which exhibits only a monomorphic smectic A phase. In order to investigate the effect of mesogenic core geometry on the mesophase properties, a comparison was established between the mesomeric behaviors of the present complexes and previously reported rigid core acid complexes. Finally, the XRD pattern confirmed the POM and DSC results.
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39

Wang, Xiangke, Dong Wang, Hong Gao, Zhou Yang, Hui Cao, Huai Yang, Wanli He, Huihui Wang, Jianming Gu y Huiying Hu. "Third-order nonlinear optical properties of a novel series of D-π-A pyrene-aldehyde derivatives". Journal of Nonlinear Optical Physics & Materials 25, n.º 02 (junio de 2016): 1650014. http://dx.doi.org/10.1142/s0218863516500144.

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A series of mono-substituted pyrene derivatives having a pyrene mesogenic core and aldehyde group peripherals were designed and synthesized, which had typical D-[Formula: see text]-A structures. Photophysical properties of the compounds were characterized by UV/Vis spectroscopy and the third-order nonlinearities of the compounds were studied by “open aperture” and “closed aperture” [Formula: see text]-scan techniques. Both of the compounds showed typical nonlinear absorptions and refractions, and the third-order nonlinear susceptibilities have been found to be very high in all cases. The significant nonlinear optical response combined with the possibility to further modify it, by changing the electron acceptor and the electron-donor groups, suggests that these systems can prove to be important candidates for a variety of photonic/optoelectronic applications.
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40

CORSELLIS, EMILY, DANIEL GUILLON, PETRA KLOESS y HARRY COLES. "Structural characterization of mono- and di-mesogenic organosiloxanes: The impact of siloxane content on biphenyl benzoate systems". Liquid Crystals 23, n.º 2 (agosto de 1997): 235–39. http://dx.doi.org/10.1080/026782997208497.

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41

Vora, R. A., R. Gupta y K. Patel. "Exhibition of Induced Mesophases in the Binary Systems where One or Both the Components are Non-Mesogenic". Molecular Crystals and Liquid Crystals 209, n.º 1 (diciembre de 1991): 251–63. http://dx.doi.org/10.1080/00268949108036200.

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42

Resetic, Andraz, Jerneja Milavec, Alexej Bubnov, Damian Pociecha, Vera Hamplova, Ewa Gorecka, Bostjan Zalar y Valentina Domenici. "New Liquid Crystalline Elastomeric Films Containing a Smectic Crosslinker: Chemical and Physical Properties". Crystals 13, n.º 1 (4 de enero de 2023): 96. http://dx.doi.org/10.3390/cryst13010096.

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Side-chain liquid crystal elastomers (SC-LCEs) have been designed by using a new smectic crosslinker. Two types of monodomain films were prepared based on polysiloxane chains, with a different relative concentration of both crosslinker and mesogenic comonomers. The mesomorphic behavior of the two SC-LCE systems was investigated by differential scanning calorimetry and polarized optical microscopy showing a different mesomorphic behavior: in one case, we obtained a nematic SC-LCE film, in the other case, a Smectic A SC-LCE film. In both systems, the mesophases were stable in a wide temperature range. Moreover, the SC-LCE films possess a relatively high orientation at room temperature. The physical-chemical properties, such as the local orientational ordering, structural organization, and dynamics of SC-LCEs’ constituents were studied by means of static and dynamic 2H NMR experiments, small-angle X-ray, and wide-angle X-ray diffractions. The relevant physical properties, such as the thermo-elastic and thermo-mechanic behaviors, are reported and discussed in view of the practical applications.
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43

George, A. K., D. M. Potukuchi, S. H. Al-Harthi y C. Carboni. "Mesomorphism in a Binary Mixture of Non-mesogens: A Dielectric Spectroscopy Investigation". Zeitschrift für Naturforschung A 59, n.º 10 (1 de octubre de 2004): 659–64. http://dx.doi.org/10.1515/zna-2004-1006.

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We report on thermal microscopy and low frequency dielectric relaxation of a liquid crystal formed by mixing cholesterol with 1-hexadecanol. Though both components are non-mesogenic, the mixture is found to exhibit a smectic A phase. A 1 Vp-p a. c signal of 100 kHz was used to study the dielectric response, while the frequency was varied from 5 Hz to 10 MHz for relaxation studies. The dielectric loss in the smectic A phase exhibits a single Debye-type off-centered relaxation in the MHz region. The temperature variation of the relaxation frequency is presented by Arrhenius plots, and the corresponding activation energy is estimated. The temperature variation of the dielectric strength (Δε =ε0 −ε∞) and the distribution parameter α in the smectic phase are estimated. The mesomorphic behavior of binary systems, where both components are non-mesomorphic, is discussed.
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44

Choi, Suk-Won, Masahito Zennyoji, Yoichi Takanishi, Hideo Takezoe, Teruki Niori y Junji Watanabe. "Structure and Switching in Bent-Shaped Molecular Liquid Crystal Systems with Two Mesogenic Groups Linked by Alkylene Spacer". Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 328, n.º 1 (agosto de 1999): 185–92. http://dx.doi.org/10.1080/10587259908026058.

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45

Birshtein, T. M., V. M. Amoskov y E. O. Smirnov. "Theory of nematic ordering in supramolecular systems: Self-assembly of mesogenic groups and self-organization of the system". Polymer Science Series A 58, n.º 4 (julio de 2016): 593–605. http://dx.doi.org/10.1134/s0965545x16040040.

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46

Frahn, Stephanie y Werner Borchard. "Phase equilibria in polymer/solvent systems, 8. Swelling of chemically crosslinked polymers in mesogenic substances in different states". Macromolecular Rapid Communications 17, n.º 7 (julio de 1996): 455–59. http://dx.doi.org/10.1002/marc.1996.030170703.

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47

Pusiol, D., F. Noack y C. Aguilera. "Proton Spin Relaxation of a Liquid Crystal with a Glassy Cholesteric State". Zeitschrift für Naturforschung A 45, n.º 9-10 (1 de octubre de 1990): 1077–84. http://dx.doi.org/10.1515/zna-1990-9-1004.

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Abstract Field-cycling and standard pulsed NMR techniques have been used to study the frequency dependence of the longitudinal proton spin relaxation time T x in the crystalline estradiol compound (+)3,1,7-ß-bis-(4n-butoxybenzoyloxy)-estra-1,3,5-(10)-trien or BET, which is a mesogenic material with a chiral molecular structure. From the measured Larmor frequency and temperature depen-dences we conclude that, at low NMR frequencies in the cholesteric phase, T1 reflects in addition to the relaxation process familiar from nematic liquid crystals (director fluctuation modes) another slow mechanism theoretically predicted for cholesteric systems, namely diffusion induced rotational molecular reorientation. These relaxation processes are not or much less effective in the crystalline and glassy state, where they are frozen. Also the high NMR frequency relaxation dispersion strongly differs between the cholesteric mesophase and the not liquid crystalline samples. This is interpreted by a change from essentially translational self-diffusion to rotational diffusion controlled proton relaxation.
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48

Koßmehl, Gerhard, Frank Dirk Hoppe y Barbara Hirsch. "Liquid Crystalline Compounds in the Thiophene Series, Part 6+ Synthesis and Characterization of Azomethines and Vinylenes with Two Mesogenic Groups and Different Alkylene Spacer Lengths". Zeitschrift für Naturforschung B 48, n.º 6 (1 de junio de 1993): 826–43. http://dx.doi.org/10.1515/znb-1993-0619.

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Compounds which have two mesogenic groups with and without terminal alkyl chains containing thiophene systems, were prepared from α.ω-bis(5-formyl-2-thienyl)alkanes (3a-3n) and various aromatic amines or 2-fluorenyl-Wittig-salt (10). The liquid crystalline properties of these compounds were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Only the series of α.ω-bis{5-[N-(4′-butyloxybiphenyl-4-yl)imino]formyl-2-thienyl}alkanes (7a-71) showed enantiotropic smectic and nematic mesophases. The series of E,E-α.ω-bis[5-(2-fluorenylvinyl)-2-thienyl]alkanes (8a-81) showed enantiotropic nematic mesophases for the compounds with 4 and 6 methylene groups, monotropic nematic mesophases for the compounds with 7—12 methylene groups and no liquid crystalline phases for compounds with 3, 5, 16 methylene groups in the connecting alkylene chain. In contrast to the compounds 8a-81, E-l-(5-butyl-2-thienyl)-2-(2-fluorenyl)ethylene has a smectic mesophase.
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49

Alhaddad, Omaima A., Hoda A. Ahmed, Mohamed Hagar, Gamal R. Saad, Khulood A. Abu Al-Ola y Magdi M. Naoum. "Thermal and Photophysical Studies of Binary Mixtures of Liquid Crystal with Different Geometrical Mesogens". Crystals 10, n.º 3 (20 de marzo de 2020): 223. http://dx.doi.org/10.3390/cryst10030223.

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Three binary systems were prepared by mixing of two different mesogenic derivatives, homologues, the first is azo/ester, namely 4-alkoxyphenylazo-4′-phenyl-4″-alkoxybenzoates (IIn+m) and the second is Schiff base/ester, namely 4-(arylideneamino)phenyl-4″-alkoxy benzoates (In+m). The two corresponding analogues from both series in the binary mixtures investigated are of the same terminal alkoxy chain length. Mesomorphic properties were investigated by differential scanning calorimetry (DSC) and phases identified by polarized optical microscope (POM). Photophysical studies were investigated by UV spectroscopy connected to a hot stage. Results were discussed based on constructed binary phase diagrams. All mixtures were found to exhibit eutectic compositions, with linear or slightly linear nematic and smectic A stability/composition dependences. Geometrical parameters were predicted applying density functional theory (DFT) calculations. Twist angle (θ), aspect ratio, dipole moment and the polarizability of the individual compounds were discussed and correlated with the experimental results to illustrate the enhanced the mesophase stability and the mesophase range of the mixture at the eutectic composition compared with those of their individual components.
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50

Volchek, B. Z., N. S. Kholmuradov, A. V. Purkina, A. Yu Bilibin y S. S. Skorokhodov. "Formation of mixed thermotropic liquid crystalline systems based on aromatic polyesters with mesogenic and flexible fragments in the main chain". Polymer Science U.S.S.R. 29, n.º 5 (enero de 1987): 1217–24. http://dx.doi.org/10.1016/0032-3950(87)90140-7.

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