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DY: Fachverband Dynamik und Statistische Physik

DY 32: Complex Fluids and Colloids, Micelles and Vesicles (joint session CPP/DY)

DY 32.7: Vortrag

Mittwoch, 18. März 2020, 11:00–11:15, ZEU 114

Lyotropic liquid crystals in microfluidic environments — •Anshul Sharma and Anupam Sengupta — Physics of Living Matter Group, University of Luxembourg, Luxembourg City, Luxembourg

Recent progress in liquid crystal microfluidics has demonstrated how hydrodynamics, in combination with confinement and surface anchoring, can be harnessed to generate tunable flow and topological structures [1, 2]. Lyotropic liquid crystals (LLCs), solutions of disc-shaped amphiphilic mesogens with aromatic core, form linear stacks that aggregate to show nematic or columnar LC phases as a function of temperature or mesogen concentration. LLCs have long been studied for their role in drug and dye manufacturing, and more recently in rapid detection of pathogens. Yet, we lack a fundamental understanding of the response of LLC to micro-scale flows a universal parameter in medical, cellular and industrial settings. With aqueous solution of disodium cromoglycate as our model LLC, we study its behavior under different concentrations and micro-scale flow regimes. Static and flow-induced textures characterized using polarizing microscopy, conoscopy and particle tracking techniques, show emergence of distinctly oriented micro-domains in the flowing LLC. Our results indicate that, for a given surface anchoring, the domain size and lifetime vary with channel geometry and flow speed. Such spontaneous orientational domains could be harnessed to generate locally distinct transport properties within a globally advected material. [1] Sengupta et al., Liquid Crystals Reviews 2, 2014. [2] Giomi et al., PNAS 114, 2017. [3] Sharma et al. (in prep.)