Direct structural observation of the alignment and elongation in lyotropic chromonic liquid crystals under shear flow

ABSTRACT

The structural characterization of the orientation and elongation under shear flow in Lyotropic Chromonic Liquid Crystals (LCLCs) molecules, Sunset Yellow FCF (SSY), was performed by in situ rheological small/wide angle X-ray scattering (Rheo-SAXS/WAXS). The X-ray measurement results clearly demonstrated that the stacked aggregates were oriented and elongated to the shear direction under shear flow. Further shear rate increase caused the enhancement in the orientation and elongation with the inter-aggregate distance constant, and then the structural change decreased implying the onset of the orientation saturation at high shear rates.

KEYWORDS:

• Lyotropic chromonic liquid crystals (LCLCs)
• sunset Yellow FCF (SSY)
• orientation
• elongation
• shear flow
• rheological small/wide angle X-ray scattering (rheo-SAXS/WAXS)

Acknowledgments

The synchrotron radiation experiments were performed at the BL08B2 in the SPring-8 with the approval of Hyogo prefecture and the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal number 2014B3326 and 2015B3326).