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Title: Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals

Abstract

A binary mixture of abietic acid and orthophosphoric acid (H{sub 3}PO{sub 4}) exhibits co-existence of biphasic region of Nematic+Isotropic (N+I), lyotropic Nematic (ND) and Smectic-G (SmG) phases. The mixture exhibits N+I, N and SmG phases at different concentrations and at different temperatures. Mixtures with all concentrations of abietic acid exhibit I→N+I→N→SmG phases sequentially when the specimen is cooled from its isotropic melt. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies.

Authors:
;  [1]; ; ;  [2]
  1. Post-Graduate Department of Physics, Government College (Autonomous), Mandya-571401 (India)
  2. Government College for Boys, Kolar-563101 (India)
Publication Date:
OSTI Identifier:
22490207
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1665; Journal Issue: 1; Conference: 59. DAE solid state physics symposium 2014, Tamilnadu (India), 16-20 Dec 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABUNDANCE; BINARY MIXTURES; CALORIMETRY; CONCENTRATION RATIO; DIFFERENTIAL THERMAL ANALYSIS; LIQUID CRYSTALS; PHASE STABILITY; PHASE STUDIES; PHOSPHORIC ACID; SMECTITE; TEMPERATURE DEPENDENCE; TEXTURE; X-RAY DIFFRACTION

Citation Formats

Govindaiah, T. N., E-mail: tngovi.phy@gmail.com, Sreepad, H. R., Sridhar, K. N., Sridhara, G. R., and Nagaraja, N. Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals. United States: N. p., 2015. Web. doi:10.1063/1.4917616.
Govindaiah, T. N., E-mail: tngovi.phy@gmail.com, Sreepad, H. R., Sridhar, K. N., Sridhara, G. R., & Nagaraja, N. Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals. United States. doi:10.1063/1.4917616.
Govindaiah, T. N., E-mail: tngovi.phy@gmail.com, Sreepad, H. R., Sridhar, K. N., Sridhara, G. R., and Nagaraja, N. Wed . "Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals". United States. doi:10.1063/1.4917616.
@article{osti_22490207,
title = {Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals},
author = {Govindaiah, T. N., E-mail: tngovi.phy@gmail.com and Sreepad, H. R. and Sridhar, K. N. and Sridhara, G. R. and Nagaraja, N.},
abstractNote = {A binary mixture of abietic acid and orthophosphoric acid (H{sub 3}PO{sub 4}) exhibits co-existence of biphasic region of Nematic+Isotropic (N+I), lyotropic Nematic (ND) and Smectic-G (SmG) phases. The mixture exhibits N+I, N and SmG phases at different concentrations and at different temperatures. Mixtures with all concentrations of abietic acid exhibit I→N+I→N→SmG phases sequentially when the specimen is cooled from its isotropic melt. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies.},
doi = {10.1063/1.4917616},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1665,
place = {United States},
year = {Wed Jun 24 00:00:00 EDT 2015},
month = {Wed Jun 24 00:00:00 EDT 2015}
}
  • Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (T{sub c}) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.
  • Dense multicomponent systems with macromolecules and small solutes attract a broad research interest as they mimic the molecularly crowded cellular interiors. The additives can condense and align the macromolecules, but they do not change the degree of covalent polymerization. We chose a lyotropic chromonic liquid crystal with reversibly and non-covalently assembled aggregates as a much softer system, reminiscent of 'living polymers', to demonstrate that small neutral and charged additives cause condensation of aggregates with ensuing orientational and positional ordering and nontrivial morphologies of phase separation, such as tactoids and toroids of the nematic and hexagonal columnar phase coexisting with themore » isotropic melt. Scanning transmission X-ray microscopy (STXM) with near edge X-ray absorption fine structure (NEXAFS) analysis as well as fluorescent microscopy demonstrates segregation of the components. The observations suggest that self-assembly of chromonic aggregates in the presence of additives is controlled by both entropy effects and by specific molecular interactions and provide a new route to the regulated reversible assembly of soft materials formed by low-molecular weight components.« less
  • Dense multicomponent systems with macromolecules and small solutes attract a broad research interest as they mimic the molecularly crowded cellular interiors. The additives can condense and align the macromolecules, but they do not change the degree of covalent polymerization. We chose a lyotropic chromonic liquid crystal with reversibly and non-covalently assembled aggregates as a much softer system, reminiscent of 'living polymers', to demonstrate that small neutral and charged additives cause condensation of aggregates with ensuing orientational and positional ordering and nontrivial morphologies of phase separation, such as tactoids and toroids of the nematic and hexagonal columnar phase coexisting with themore » isotropic melt. Scanning transmission X-ray microscopy (STXM) with near edge X-ray absorption fine structure (NEXAFS) analysis as well as fluorescent microscopy demonstrates segregation of the components. The observations suggest that self-assembly of chromonic aggregates in the presence of additives is controlled by both entropy effects and by specific molecular interactions and provide a new route to the regulated reversible assembly of soft materials formed by low-molecular weight components.« less