Aggregation-driven, re-entrant isotropic phase in a smectic liquid crystal material

Jonathan G. Fernsler; Matthew A. Glaser; Renfan Shao; David A. Coleman; Joseph E. Maclennan; Darren R. Link; Catherine Chang; Kenneth Lanham; David Walba; Cecile Boyer; Joseph A. Zasadzinski; Noel A. Clark

doi:10.1080/02678292.2016.1240835

Aggregation-driven, re-entrant isotropic phase in a smectic liquid crystal material

Jonathan G. Fernsler, Matthew A. Glaser, Renfan Shao, David A. Coleman, Joseph E. Maclennan, Darren R. Link, Catherine Chang, Kenneth Lanham, David Walba, Cecile Boyer, Joseph A. Zasadzinski, Noel A. Clark

Chemical Engineering and Materials Science

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

An azobenzene-core chiral mesogen designed for a photoactive ferroelectric liquid crystal system with switchable polarisation displays a highly unusual phase sequence, with a re-entrant, optically isotropic, fluid phase found below smectic phases in mixtures with high enantiomeric purity. The re-entrant isotropic phase is found on the basis of X-ray scattering and freeze-fracture transmission electron microscopy experiments not to be a cubic or other highly ordered phase but instead a translationally disordered liquid. The material also forms a gel under a wide range of concentrations in 50:50 ethanol/chloroform solutions. Ultraviolet/visible and infrared spectroscopy and quantum chemistry calculations suggest that the primary unit in the re-entrant isotropic and gel phases is a dimer composed of molecules crossed by about 90°, which hinders the formation of crystal phases and forms tubules of helical aggregates in the gel phase.

Original language	English (US)
Pages (from-to)	769-783
Number of pages	15
Journal	Liquid Crystals
Volume	44
Issue number	5
DOIs	https://doi.org/10.1080/02678292.2016.1240835
State	Published - Apr 9 2017

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation [Grant Numbers DMR-0820579 and DMR-1420736].

Publisher Copyright:
© 2016 Informa UK Limited, trading as Taylor & Francis Group.

Keywords

Smectic
azobenzene dye
chirality
gel
re-entrant phase transition

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10.1080/02678292.2016.1240835

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abstract = "An azobenzene-core chiral mesogen designed for a photoactive ferroelectric liquid crystal system with switchable polarisation displays a highly unusual phase sequence, with a re-entrant, optically isotropic, fluid phase found below smectic phases in mixtures with high enantiomeric purity. The re-entrant isotropic phase is found on the basis of X-ray scattering and freeze-fracture transmission electron microscopy experiments not to be a cubic or other highly ordered phase but instead a translationally disordered liquid. The material also forms a gel under a wide range of concentrations in 50:50 ethanol/chloroform solutions. Ultraviolet/visible and infrared spectroscopy and quantum chemistry calculations suggest that the primary unit in the re-entrant isotropic and gel phases is a dimer composed of molecules crossed by about 90°, which hinders the formation of crystal phases and forms tubules of helical aggregates in the gel phase.",

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author = "Fernsler, {Jonathan G.} and Glaser, {Matthew A.} and Renfan Shao and Coleman, {David A.} and Maclennan, {Joseph E.} and Link, {Darren R.} and Catherine Chang and Kenneth Lanham and David Walba and Cecile Boyer and Zasadzinski, {Joseph A.} and Clark, {Noel A.}",

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AU - Fernsler, Jonathan G.

AU - Glaser, Matthew A.

AU - Shao, Renfan

AU - Coleman, David A.

AU - Maclennan, Joseph E.

AU - Link, Darren R.

AU - Chang, Catherine

AU - Lanham, Kenneth

AU - Walba, David

AU - Boyer, Cecile

AU - Zasadzinski, Joseph A.

AU - Clark, Noel A.

N1 - Funding Information: This work was supported by the National Science Foundation [Grant Numbers DMR-0820579 and DMR-1420736]. Publisher Copyright: © 2016 Informa UK Limited, trading as Taylor & Francis Group.

PY - 2017/4/9

Y1 - 2017/4/9

N2 - An azobenzene-core chiral mesogen designed for a photoactive ferroelectric liquid crystal system with switchable polarisation displays a highly unusual phase sequence, with a re-entrant, optically isotropic, fluid phase found below smectic phases in mixtures with high enantiomeric purity. The re-entrant isotropic phase is found on the basis of X-ray scattering and freeze-fracture transmission electron microscopy experiments not to be a cubic or other highly ordered phase but instead a translationally disordered liquid. The material also forms a gel under a wide range of concentrations in 50:50 ethanol/chloroform solutions. Ultraviolet/visible and infrared spectroscopy and quantum chemistry calculations suggest that the primary unit in the re-entrant isotropic and gel phases is a dimer composed of molecules crossed by about 90°, which hinders the formation of crystal phases and forms tubules of helical aggregates in the gel phase.

AB - An azobenzene-core chiral mesogen designed for a photoactive ferroelectric liquid crystal system with switchable polarisation displays a highly unusual phase sequence, with a re-entrant, optically isotropic, fluid phase found below smectic phases in mixtures with high enantiomeric purity. The re-entrant isotropic phase is found on the basis of X-ray scattering and freeze-fracture transmission electron microscopy experiments not to be a cubic or other highly ordered phase but instead a translationally disordered liquid. The material also forms a gel under a wide range of concentrations in 50:50 ethanol/chloroform solutions. Ultraviolet/visible and infrared spectroscopy and quantum chemistry calculations suggest that the primary unit in the re-entrant isotropic and gel phases is a dimer composed of molecules crossed by about 90°, which hinders the formation of crystal phases and forms tubules of helical aggregates in the gel phase.

KW - Smectic

KW - azobenzene dye

KW - chirality

KW - gel

KW - re-entrant phase transition

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Aggregation-driven, re-entrant isotropic phase in a smectic liquid crystal material

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