Structure-Property Relationships in the Twist-Bend Liquid Crystal Phase of Odd Members of the CBnCB Homologous Series

ORAL

Abstract

We synthesize a series of homologues of CB7CB with different alkyl number n in the linker to investigate the effects of linker length on the properties of the twist-bend phase. We identify the TB phase in the odd members of the CBnCB series for n = 5 – 17 and investigate them primarily with resonant soft x-ray scattering (RSoXS) and non-resonant wide-angle x-ray scattering techniques. Increasing the length of the linker increases the molecular flexibility and decouple the mesogenic arms of the molecules, tending to stabilize the temperature range of the nematic phase while that of the TB phase diminishes. It also dramatically increases the helix pitch and contributes to enhanced structural fluctuations of the helix. We fit the measured helix pitch as a function of temperature for each compound to extract its ground state pitch at low temperature, when fluctuations are frozen out. We find that the ground state helix pitch scales nearly linearly with linker number. Our study not only demonstrates the nanoscale effects of lengthening the chemical linker, but also highlights the surprising importance of fluctuations in the behavior of the twist-bend phase.

*This work is supported by MRSEC NSF DMR 1420736 and NSF DMR 1710711.

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Presenters

  • Michael Tuchband

    • Department of Physics and Soft Materials Research Center, University of Colorado, Boulder
    • Soft Materials Research Center, University of Colorado, Boulder

Authors

  • Michael Tuchband

    • Department of Physics and Soft Materials Research Center, University of Colorado, Boulder
    • Soft Materials Research Center, University of Colorado, Boulder

  • Min Shuai

    • Physics, Univ of Colorado - Boulder
    • Department of Physics and Soft Materials Research Center, University of Colorado, Boulder

  • Daniel Paterson

    • Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen

  • Lee Foley

    • Department of Chemistry and Biochemistry and Soft Materials Research Center, University of Colorado, Boulder

  • Jessica Riano

    • Department of Chemistry and Biochemistry and Soft Materials Research Center, University of Colorado, Boulder

  • Alyssa Scarbrough

    • Department of Chemistry and Biochemistry and Soft Materials Research Center, University of Colorado, Boulder

  • Victoria Normal

    • Advanced Light Source, Lawrence Berkeley National Laboratory

  • Cheng Wang

    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley Natl Lab
    • Lawrence Berkeley Natl Lab
    • Lawrence Berkeley National Lab

  • David Walba

    • Department of Chemistry and Biochemistry and Soft Materials Research Center, University of Colorado, Boulder

  • John Storey

    • Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen

  • Chenhui Zhu

    • Advanced Light Source, Lawrence Berkeley Natl Lab
    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • Lawrence Berkeley Natl Lab

  • Corrie Imrie

    • Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen

  • Noel Clark

    • Physics, Univ of Colorado
    • Physics, Univ of Colorado - Boulder
    • Department of Physics and Soft Materials Research Center, University of Colorado, Boulder
    • Soft Materials Research Center, University of Colorado, Boulder