Indication of a Twist-Grain-Boundary-Twist-Bend Phase of flexible bent-shape chiral dimers.

ORAL

Abstract

Flexible bent-core oligomers with odd-numbered methylene spacers exhibit a “twist-bend” nematic (NTB) phase characterized by a nanoscale heliconical pitch. We designed mixtures of achiral dimers, which exhibit the NTB phase, with a chiral additive. By differential scanning calorimetry, resonant soft X-ray scattering, polarized optical microscopy, and induced circular dichroism studies on condensed phases of these mixtures, we find, while in the nematic phase the micron-scale pitch of the additive-induced helical structure decreases with increasing additive concentration, in the N phase both the micron-scale and the nanoscale pitch of the ambidextrous spontaneous heliconical structure increase. At chiral additive concentrations above ~2% by weight, a new phase appears between the N* and NTB* phases, which we propose to be analogous to the twist-grain-boundary (TGB) phase of chiral smectics; we designate this new phase by TGBTB.

*This work was supported by U.S. National Science Foundation (NSF) DMR-1506018 and DMR 1307674 and NSF REU CHE-1659571. Beamline 11.0.1.2 at Advanced Light Source at Lawrence Berkeley National Laboratory are supported by Director of the Office of Science, Office of Basic Energy Sciences, of U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.

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Presenters

  • Matthew Murachver

    • Chemical Physics Interdisciplinary Program, Kent State University

Authors

  • Matthew Murachver

    • Chemical Physics Interdisciplinary Program, Kent State University

  • Ahlam Nemati

    • Chemical Physics Interdisciplinary Program, Kent State University
    • Advanced Materials & Liquid Crystal Institute, Kent State University

  • Carson Bullock

    • Department of Physics, College of Wooster

  • Zachary Sabata

    • Department of Physics, Unversity of Nebraska, Omaha

  • Haumed Rahmani

    • Chemical Physics Interdisciplinary Program, Kent State University

  • Tetiana Vorobiova

    • Chemical Physics Interdisciplinary Program, Kent State University

  • Miroslaw Salamonczyk

    • Faculty of Chemistry, University of Warsaw
    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Alain Izadnegahdar

    • Advanced Precision Systems

  • Seyyed Salili

    • Department of Physics & Astronomy, University of Pennsylvania

  • Victoria Norman

    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Chenhui Zhu

    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Torsten Hegmann

    • Chemical Physics Interdisciplinary Program, Kent State University
    • Advanced Materials & Liquid Crystal Institute, Kent State University

  • Samuel N Sprunt

    • Department of Physics, Kent State University

  • James Gleeson

    • Department of Physics, Kent State University, Kent, OH USA
    • Department of Physics, Kent State University
    • Kent State University

  • Antal Istvan Jakli

    • Liquid Crystal Institute, Kent State University
    • Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University
    • Chemical Physics Interdisciplinary Program, Liquid Crystal Institute, Kent State University, Kent, OH USA
    • Chemical Physics Interdisciplinary Program, Kent State University
    • Advanced Materials & Liquid Crystal Institute, Kent State University
    • Kent State University
    • Department of Physics, Kent State University,Kent, OH 44240, USA