Liquid-crystalline properties of 4-alkyl-, 4-alkyloxy and 4-halogene-4′-hydroxyazobenzene alkyloates

2009 ◽  
Vol 17 (2) ◽  
Author(s):  
J. Trzaska ◽  
Z. Galewski
Keyword(s):  
Liquid Crystalline ◽  
Polarizing Microscopy ◽  
Crystalline Polymorphism ◽  
Dsc Calorimetry

AbstractTwenty one esters, 4-alkyl-, 4-alkyloxy-, 4-nitro- and 4-halogene-4′-hydroxyazobenzne alkyloates have been synthesised. Basing on the DSC calorimetry and polarizing microscopy liquid- crystalline polymorphism was investigated. Five types of mesophases were identified: nematic, smectics A, C, F and unknown X (probably G).

Influence of terminal groups on liquid-crystalline polymorphism of selected azobenzene derivatives

2013 ◽  
Vol 41 (1) ◽  
pp. 113-125 ◽  
Author(s):  
Marta Podruczna ◽  
Anna Hofmańska ◽  
Izabela Niezgoda ◽  
Damian Pociecha ◽  
Zbigniew Galewski
Keyword(s):  
Liquid Crystalline ◽  
Crystalline Polymorphism ◽  
Azobenzene Derivatives

Synthesis, Characterization and Adsorption Performance of Semi-crystalline/Liquid Crystalline Polyether Chelating Resins

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Shuangqing Zhang ◽  
Chaocan Zhang ◽  
Changhai He ◽  
Jun Xu
Keyword(s):  
Adsorption Capacity ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Selective Adsorption ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Adsorption Ability ◽  
H Nmr ◽  
Chelating Resins ◽  
Crystal Polymer

AbstractA series of polyether chelating resins with pendent biphenyl mesogenic groups were synthesized, and the chemical structure of monomers and polymers were confirmed by IR and 1H NMR detection. The thermal properties of resins were investigated by the Differential Scanning Calorimetry (DSC) and Polarizing Microscopy (POM), and the results showed that only the product of polyepichlorohydrin grafted with 4-cyano-4’-hydrobiphenyl, i.e., HPCN resin, was a kind of nematic liquid crystal polymer with typical schlieren texture (70-130 0C) and other resins were semi-crystalline. The results of adsorption experiments showed that all five resins exhibited a higher adsorption capacity (>1.0 mmol/g) for Cu (II) and Hg (II) and medium adsorption ability for Cd (II), Zn (II), Pb (II) and Co (II), however, a poor adsorption capacity (<0.3 mmol/g) for Mg (II), indicating that this type of polyether resins have a better selective adsorption for above metal ions. In addition, the adsorption capacity of HPnCP resins was generally higher than that of HPd and HPCN owing to the existence of terminal pyrrole coordination groups in HPnCP resins.

Self-Recognition and Self-Assembly of Folic Acid Salts: Columnar Liquid Crystalline Polymorphism and the Column Growth Process

1994 ◽  
Vol 116 (16) ◽  
pp. 7064-7071 ◽  
Author(s):  
Federica Ciuchi ◽  
Giovanni Di Nicola ◽  
Hermann Franz ◽  
Giovanni Gottarelli ◽  
Paolo Mariani ◽  
...  
Keyword(s):  
Folic Acid ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Growth Process ◽  
Self Recognition ◽  
Crystalline Polymorphism ◽  
Acid Salts

scholarly journals Rheological Investigation of Self-emulsification Process

2009 ◽  
Vol 12 (1) ◽  
pp. 17 ◽  
Author(s):  
Shailesh V Biradar ◽  
Ravindra S Dhumal ◽  
Anant Paradkar
Keyword(s):  
Liquid Crystalline ◽  
Bound Water ◽  
Tween 80 ◽  
Cubic Phase ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Rheological Analysis ◽  
Mesophase Formation ◽  
High Level ◽  
Emulsification Process

PURPOSE Aim of this study is to investigate the mechanism of self-emulsification through rheological analysis of intermediate liquid crystalline (LC) phase formed during self-emulsification process. METHODS Binary system of tween 80 (T80) and imwitor 742 (I742) was used and different SES were prepared with I742 at 10, 30, 50, 70 and 90% w/w concentration levels. Self-emulsification was monitored by visual observations and droplet size measurement. Mesophases obtained by 50% v/v hydration of SES were utilized for polarizing microscopy, differential scanning calorimetry and rheological studies. RESULTS Good emulsification with nano sized droplets was observed for SES 30% as compared to micron sized droplets for other SES. In polarizing microscopy, formation of intermediate LC phase was observed in all SES. Lamellar phase was evident in 30% SES while other SES exhibited micellar cubic phase. Presence of high level of structurally bound water in thermal analysis confirmed mesophase formation in all SES. In frequency sweep, decrease in elastic modulus, and an increase in phase degree and loss tangent was observed for 30% SES. Exactly opposite trend was seen in other SES. Thus, rheological studies concluded presence of weak and fragile mesophase structure in 30% SES while LC phase structure with little structural buildup was observed in other SES. This weak mesosphere structure in SES 30% presented no or very little resistance against strain induced deformation. Therefore, during emulsification, weak mesophase in SES 30% ruptured with ease and released jet of nanosize droplets compared to coarse droplets for other SES. CONCLUSION This study signifies the effect of viscoelastic properties of intermediate LC phase on self-emulsification performance.

scholarly journals 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

1993 ◽  
Vol 48 (6) ◽  
pp. 826-843 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Frank Dirk Hoppe ◽  
Barbara Hirsch
Keyword(s):  
Aromatic Amines ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Alkyl Chains ◽  
Liquid Crystalline Phases ◽  
Smectic Mesophase ◽  
Methylene Groups

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.

Polycatenar mesogens with a perfluorinated moiety showing a variety of liquid crystalline polymorphism

2005 ◽  
Vol 32 (5) ◽  
pp. 585-598 ◽  
Author(s):  
Etsushi Nishikawa ◽  
Jun Yamamoto ◽  
Hiroshi Yokoyama
Keyword(s):  
Liquid Crystalline ◽  
Crystalline Polymorphism

Thin Films of Liquid Crystalline Phthalocyanines and their its Composites with Single-Walled Carbon Nanotubes: Properties and Alignment

2012 ◽  
Vol 531-532 ◽  
pp. 337-341
Author(s):  
Tamara Basova ◽  
Aliye Aslı Esenpinar ◽  
Sinem Tuncel ◽  
Mahmut Durmuş ◽  
Ayşe Gül Gürek ◽  
...  
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Spin Coating ◽  
Liquid Crystalline ◽  
Copper Phthalocyanine ◽  
Single Walled Carbon Nanotubes ◽  
Polarizing Microscopy ◽  
Single Walled Carbon ◽  
Polarized Raman ◽  
Walled Carbon Nanotubes

In this study, liquid crystalline copper phthalocyanine and single walled carbon nanotubes were dispersed in solution to prepare novel composites. Thin films of these composites prepared by solving of the composite in dimetylformamide and then by spin coating the solution onto the substrates were studied by the methods of polarizing microscopy, polarized Raman and optical absorption spectroscopies. It was shown that pure CuPcR4forms the films with a herringbone arrangement of phthalocyanine molecules within adjacent columns. An addition of carbon nanotubes (0.5-2 wt %) to CuPcR4leads to formation of the films with edge-on orientation of the molecules. The higher conductivity values were found for the films of phthalocyanine containing SWCNT. The lateral conductivity tends to decrease with the increase of SWCNT concentration from 0.5 to 2 wt %.

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