Homeotropic alignment of the lyotropic chromonic liquid crystal Sunset Yellow FCF using pi-pi stacking chemical interactions

ORAL

Abstract

We report on the homeotropic alignment of the lyotropic chromonic liquid crystal, Sunset Yellow FCF (SSY), using pi-pi stacking interactions between the SSY molecules and (1) thin parylene films or (2) a graphene monolayer. The nematic and columnar phases of SSY molecules arise via self-assembly in water into stacks through non-covalent attractions between the SSY molecules. Interestingly, we find that the same non-covalent interactions between SSY molecules and a parylene or graphene alignment layer lead to homeotropic anchoring of these stacks. The nematic phase of SSY is introduced between two glass substrates coated with parylene films or graphene monolayers, and homeotropic alignment of SSY is confirmed by polarized optical microscopy and conoscopy. Additionally, we observe and can explain the stripe domains that occur during cooling of the sample in this cell, and we consider possible novel applications for homeotropically aligned chromonic liquid crystals.

*We gratefully acknowledge financial support from the National Science Foundation through NSF DMR-1205463 and UPENN MRSEC DMR-1120901

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Authors

  • Joonwoo Jeong

    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA

  • Gang Hee Han

    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
    • University of Pennsylvania

  • A.T. Charlie Johnson

    • University of Pennsylvania
    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA

  • Tom C. Lubensky

    • University of Pennsylvania
    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA

  • Peter Collings

    • Department of Physics \& Astronomy, Swarthmore College, Swarthmore, PA 19081
    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
    • Swarthmore College, Department of Physics

  • Arjun G. Yodh

    • Department of Physics and Astronomy, University of Pennsylvania
    • University of Pennsylvania, Department of Physics and Astronomy
    • University of Pennsylvania
    • Department of Physics \& Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA