  Nematic and columnar phases of lyotropic chromonic liquid crystals (LCLCs)
have been long studied for their fundamental and applied prospects in material
science and medical diagnostics. LCLC phases represent different self-assembled
states of disc-shaped molecules, held together by noncovalent interactions that
lead to highly sensitive concentration and temperature dependent properties.
Yet, microscale insights into confined LCLCs, specifically in the context of
confinement geometry and surface properties, are lacking. Here, we report the
emergence of time dependent textures in static disodium chromoglycate (DSCG)
solutions, confined in PDMS-based microfluidic devices. We use a combination of
soft lithography, surface characterization and polarized optical imaging to
generate and analyze the confinement-induced LCLC textures, and demonstrate
that over time, herringbone and spherulite textures emerge due to spontaneous
nematic (N) to columnar M-phase transition, propagating from the LCLC-PDMS
interface into the LCLC bulk. By varying the confinement geometry, anchoring
conditions and the initial DSCG concentration, we can systematically tune the
temporal dynamics of the N to M-phase transition and textural behaviour of the
confined LCLC. Since static molecular states register the initial conditions
for LC flows, the time dependent boundary and bulk conditions reported here
suggest that the local surface-mediated dynamics could be central in
understanding LCLC flows, and in turn, the associated transport properties of
this versatile material.
