Comparison of material parameters among flexible dimer, trimer, tetramer of nematic mesogens

ORAL

Abstract

We compare the temperature dependencies of the birefringence, elastic constants and orientational viscosities for four homologous nematic liquid crystal oligomers: dimer (DTC5C9), its associated trimer and tetramer. These materials all exhibit the twist-bend nematic (NTB) phase. The magnitudes of the splay (K11), twist (K22) and bend (K33) elastic constants, as well as the corresponding orientational viscosities are determined by dynamic light scattering measurements. Interestingly K33 in the dimer and tetramer shows the monotonic decrease with temperature below the nematic-isotropic transition followed by a pretransitional increase close to the nematic to NTB transition. The trimer, in contrast, shows essentially no pretransitional change in K33 . This behavior can be attributed to odd-even effect associated with the number of monomer unites in oligomers. The orientational viscosities associated with splay, twist and bend fluctuations in the N phase of dimer, trimer and tetramer are comparable to those of nematics formed by rod-like molecules. All three show strong temperature dependence, increasing sharply near the N – NTB transition.

References
[1] G.Babakhanova, et.al ,Physical Review E, 96 (6), 062704 (2017)

*The work was supported by NSF grants DMR-1410378 and DMR-1307674.

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Presenters

  • Zeinab Parsouzi A.Sh

    • Kent State University

Authors

  • Zeinab Parsouzi A.Sh

    • Kent State University

  • Greta Babakhanova

    • Kent State University
    • Chemical Physics Interdisciplinary Program, Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA

  • Rony Saha

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

  • Mojtaba Rajabi

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

  • Taras Turiv

    • Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio, 44242, USA
    • Advanced Materials Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University
    • Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University
    • Advanced Materials and Liquid Crystal Institute, Kent State Univeristy
    • Kent State University
    • Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program, Kent State University

  • Chris Welch

    • Department of Chemistry, University of Hull, Hull, UK

  • Georg H Mehl

    • Department of Chemistry, University of Hull, Hull, UK

  • 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

  • O D Lavrentovich

    • Kent State University
    • Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio, 44242, USA
    • Department of Physics and Advanced Materials Liquid Crystal Institute, Kent State University
    • Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program and Physics Department, Kent State University
    • Advanced Materials and Liquid Crystal Institute, Kent State Univeristy
    • Advanced Materials and Liquid Crystal Institute / Department of Physics, Kent State University, Kent, OH 44242, USA
    • Department of Physics, Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program, Kent State University

  • Samuel Sprunt

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