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.

Synthesis and Characterization of Stilbene Derivatives for Possible Incorporation as Smart Additives in Polymers Used as Packaging Films.

1997 ◽  
Vol 50 (4) ◽  
pp. 425 ◽  
Author(s):  
Gary M. Day ◽  
Owen T. Howell ◽  
Michael R. Metzler ◽  
Paul D. Woodgate
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Packaging Films ◽  
Multiple Phase ◽  
Liquid Crystalline Phases ◽  
Crystal Properties ◽  
Stilbene Derivatives

Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.

Liquid Crystalline Compounds in the Thiophene Series, Part 12+ Synthesis and Characterization of Side Chain Polysiloxanes with Low Transition Temperatures

1996 ◽  
Vol 51 (2) ◽  
pp. 286-294 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Bettina Labahn
Keyword(s):  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Terminal Group ◽  
Side Chain ◽  
Synthesis And Characterization ◽  
Crystalline Solid ◽  
Isotropic Liquid ◽  
Liquid Crystalline Phases ◽  
Methylene Groups

Abstract Polysiloxanes as side chain polymers containing the 2.2′-bithiophene unit, hexyl and octyl terminal groups and spacer units with 3, 5. 6 and 10 methylene groups were prepared and characterized. These polymers have monotropic liquid crystalline phases with transition tem ­ peratures below 0 °C (e. g. for polymer 6p: isotropic → liquid crystalline transition: -20 °C; liquid crystalline → solid transition: -43 °C). Polymers with a trimethylene spacer group must contain an octyl terminal group for forming liquid crystalline phase; a hexyl group does not form such a phase.

Synthesis and characterization of novel dibenz[a,c]anthracenedicarboxythioimides: the effect of thionation on self-assembly

RSC Advances ◽  
2016 ◽  
Vol 6 (82) ◽  
pp. 78784-78790 ◽  
Author(s):  
Katie. M. Psutka ◽  
Kenneth E. Maly
Keyword(s):  
Self Assembly ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Crystalline Phases ◽  
Liquid Crystalline Phases ◽  
Self Association

The effect of thionation on the formation of columnar liquid crystalline phases of dibenzanthracenedicarboximides as well as their self-association in solution is described.

scholarly journals Synthesis, Mesomorphism and the Optical Properties of Alkyl-deuterated Nematogenic 4-[(2,6-difluorophenyl)ethynyl]biphenyls

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4653
Author(s):  
Jakub Herman ◽  
Piotr Harmata ◽  
Michał Czerwiński ◽  
Olga Strzeżysz ◽  
Marta Pytlarczyk ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Optical Properties ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
Synthesis And Characterization ◽  
Molecular Approach ◽  
Scanning Calorimetry

The synthesis and characterization of new deuterated liquid crystal (LC) compounds based on phenyl tolane core is described in this paper. The work presents an alternative molecular approach to the conventional LC design. Correlations between molecular structure and mesomorphic and optical properties for compounds which are alkyl-hydrogen terminated and alkyl-deuterium, have been drawn. The compounds are characterized by mass spectrometry (electron ionization) analysis and infrared spectroscopy. They show enantiotropic nematic behavior in a broad temperature range, confirmed by a polarizing thermomicroscopy and differential scanning calorimetry. Detailed synthetic procedures are attached. Synthesized compounds show a significantly reduced absorption in the near-infrared (NIR) and medium-wavelength infrared (MWIR) radiation range, and stand as promising components of medium to highly birefringent liquid crystalline mixtures.

The synthesis and characterization of liquid crystalline oligoimides and polyimides

1995 ◽  
Vol 7 (4) ◽  
pp. 421-431 ◽  
Author(s):  
P Alder ◽  
J G Dolden ◽  
P Smith
Keyword(s):  
Liquid Crystalline ◽  
Solution Method ◽  
Molar Mass ◽  
Building Blocks ◽  
Decomposition Temperature ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Nematic Phases ◽  
Optical Polarizing Microscopy

There are few examples of thermotropic polyimides reported in the literature. In the present article the authors report the synthesis and characterization of some novel oligoand poly-imides which exhibit mesogenic behaviour. The solution method of Yamazaki et al (Yamazaki N, Higashi F and Kawasaki J 1974 J. Polym. Sci., Polym. Chem. Ed. 12 2149) for the preparation of polyamides was successfully applied to the formation of imide compounds and oligomers. Liquid crystal phases were characterized by optical polarizing microscopy and by differential scanning calorimetry. Two anhydrides were employed which were considered to be suitable building blocks for preparing potentially mesogenic polyimides, namely biphenyl tetracarboxytic dianhydride and pyromellitic dianhydride. Low-molar-mass materials were first synthesized with monoanhydride units to endcap the chains. using nadic and maleic anhydrides. Nematic phases Awere observed in several nadic diimide compounds containing multicyclic cores and in some low-molar-mass diimides and polyimides which contained a biphenylene unit in conjunction with at least one other unsaturated ring When the nadlmldes were heated above 220 C cross-linking and decomposition occurred with loss of mesogenic properties. A fusible polyimide was synthesized containing a flexible chain which exhibited thermotropic behaviour below its decomposition temperature.

Synthesis and Characterization of Smectic Polymorphism in Higher Homologues of N-(p-n-Alkoxybenzylidene)-p-n-(Alkylanilines)

2003 ◽  
Vol 58 (2-3) ◽  
pp. 103-108 ◽  
Author(s):  
Venkata G. K. M. Pisipati ◽  
A. K. George ◽  
Ch. Srinivasu ◽  
P. N. Murty
Keyword(s):  
Differential Scanning Calorimetry ◽  
Alkyl Chain ◽  
Synthesis And Characterization ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Phase Variants ◽  
Miscibility Studies

Higher homologues of N-(p-n-alkoxybenzylidene)-p-n-alkylanilines (nO.m) compounds with n = 15 and 18 and m = 4 to 10, 12, 14, and 16 have been synthesized and the smectic polymesomorphism is studied. The transition temperatures were obtained both from thermal polarizing microscopy and differential scanning calorimetry. The compounds exhibit a smectic-F phase from the isotropic melt, their amount increasing with the number of the alkoxy chain. This implies that with the alkoxy chain number the manifestation of smectic-F occurs with shorter alkyl chain. The phase variants were confirmed with miscibility studies

Synthesis and Characterization of Segmented Copolymers of a Methylated Polyamide and a Thermotropic Liquid Crystalline Polyester

1989 ◽  
Vol 171 ◽  
Author(s):  
Gregory T. Pawlikowski ◽  
R. A. Weiss ◽  
S. J. Huang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Composite Material ◽  
Block Copolymer ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Segmented Copolymers ◽  
Liquid Crystalline Polyester ◽  
Solution Polycondensation

ABSTRACTA block copolymer consisting of liquid crystalline polyester segments and methylated polyamide segments has been synthesized. Solution polycondensation of acid chloride end-capped poly(terephthaloyl phenylhydroquinone) (LCP portion) with an amine terminated poly(N,N'-dimethylethylene sebacamide) was utilized to prepare the block copolymer. Characterization by differential scanning calorimetry, infrared spectroscopy, thermogravimetric analysis, optical microscopy and elemental analysis has been performed to verify the existence of the block copolymer that may have potential as a molecular composite material or self-reinforcing thermoplastic.

Synthesis and Characterization of Novel Arylidene and Cardo Ester Bismaleimides and Poly(aminoaspartimide)s Therefrom

2003 ◽  
Vol 15 (3) ◽  
pp. 301-318 ◽  
Author(s):  
Vasile Cozan ◽  
Mitica Sava ◽  
Luminita Marin ◽  
Maria Bruma
Keyword(s):  
Thermal Stability ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Analysis Data ◽  
Synthesis And Characterization ◽  
Elemental Analysis Data ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
H Nmr

Six new bismaleimides (BMIs) having arylidene or cardo cycloaliphatic internal moieties were prepared by reacting 4-maleimidobenzoyl chloride with various arylidene or cardo bisphenols. The structures of BMIs were confirmed using elemental analysis data and spectroscopic (IR, 1H-NMR) characterizations. Two poly(aminoaspartimide)s (PAAs) were synthesized to exemplify one of the post-reaction abilities of the BMIs. Thermotropic liquid crystalline behavior was observed by differential scanning calorimetry and polarized light microscopy. The thermal stability of BMIs and PAAs was determined by thermogravimetric analysis and they showed good thermal stability except BMI 10, containing a cyclopentanone unit, which decomposed around 235°C. In this paper, we discuss the synthesis and characterization of these materials.

scholarly journals Synthesis and Characterization of Crown-Ether Appended Hexaazatrinaphthylene-Based Liquid-Crystalline Derivative

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 377
Author(s):  
Kyosuke Isoda ◽  
Keigo Shimooka
Keyword(s):  
Crown Ether ◽  
Electronic Properties ◽  
Intermolecular Interaction ◽  
Liquid Crystalline ◽  
Bathochromic Shift ◽  
Dipole Interaction ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Scanning Calorimetry

In this article, we report on the synthesis and characterization of crown-ether appended hexaazatrinaphthylene derivatives with two alkoxy chains. The complexation of a derivative having shorter alkoxy chains with metal ions, such as NaI and KI, prompts remarkable changes in the electronic properties of sold states, because of changing intermolecular interactions. Polarized optical microscopic observation, X-ray diffraction pattern measurement and differential scanning calorimetry reveal that a compound with longer alkoxy chains self-assembles into the formation of the columnar liquid-crystalline phase. Moreover, the addition of benzenesulphonic acid influences the self-assembled liquid-crystalline structures, as well as the electronic properties. The complexation of the derivative having longer alkoxy chains with benzenesulphonic acid induces a larger dipole moment, compared to that before complexation, thereby leading to the enhancement of intermolecular interaction, such as dipole-dipole interaction. Also, peaks in UV-vis absorption and fluorescent spectra show a dramatically bathochromic shift, due to their intermolecular interaction, such as the π-π interaction.

Synthesis and Characterization of Liquid Crystalline Polysiloxanes Containing Terminal Fluoromethyl Groups

2012 ◽  
Vol 466-467 ◽  
pp. 500-503
Author(s):  
Fan Bao Meng ◽  
Na Diao ◽  
Cui Zhi Zhu ◽  
Ri Li ◽  
Hong Mei Gao
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Polymer Systems ◽  
Chemical Structures ◽  
Nematic Mesophase ◽  
Smectic Mesophase ◽  
Temperature Ranges ◽  
Synthesized Materials

A series of liquid crystalline (LC) polysiloxanes (PI-PV) were prepared by use of poly(methylhydrogeno)siloxane and two kinds of terminal olefinic monomers. The chemical structures and liquid-crystalline properties of the synthesized materials were characterized by various experimental techniques. From PI to PV, the glass transition temperature and the isotropic temperature decreased slightly with increase of terminal fluoromethyl units in the polymer systems. All the monomers and polymers showed nematic phase with wide mesophase temperature ranges. The polymers PI, PII and PIII displayed single nematic mesophase, but PIV and PV bearing more terminal fluoromethyl units showed another smectic mesophase besides nematic mesophase.

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