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

Research output: Contribution to journalArticlepeer-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 languageEnglish (US)
Pages (from-to)769-783
Number of pages15
JournalLiquid Crystals
Volume44
Issue number5
DOIs
StatePublished - Apr 9 2017

Bibliographical note

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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