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Article

Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements

Physics of Living Matter, Department of Physics and Materials Science, University of Luxembourg, 162 A, Avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg
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Crystals 2021, 11(1), 35; https://doi.org/10.3390/cryst11010035
Received: 10 November 2020 / Revised: 18 December 2020 / Accepted: 18 December 2020 / Published: 30 December 2020
(This article belongs to the Special Issue Early Career Stars of the Decade)
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 cromoglycate (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 behavior of the confined LCLC. Overall, the time taken to change from nematic to the characteristic M-phase textures decreased as the confinement aspect ratio (width/depth) increased. For a given aspect ratio, the transition to the M-phase was generally faster in degenerate planar confinements, relative to the transition in homeotropic confinements. Since the static molecular states register the initial conditions for LC flows, the time dependent textures reported here suggest that the surface and confinement effects—even under static conditions—could be central in understanding the flow behavior of LCLCs and the associated transport properties of this versatile material. View Full-Text
Keywords: lyotropic chromonic liquid crystals; microfluidics; surface anchoring; phase transition; herringbone; spherulite; textures lyotropic chromonic liquid crystals; microfluidics; surface anchoring; phase transition; herringbone; spherulite; textures
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MDPI and ACS Style

Sharma, A.; Ong, I.L.H.; Sengupta, A. Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements. Crystals 2021, 11, 35. https://doi.org/10.3390/cryst11010035

AMA Style

Sharma A, Ong ILH, Sengupta A. Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements. Crystals. 2021; 11(1):35. https://doi.org/10.3390/cryst11010035

Chicago/Turabian Style

Sharma, Anshul, Irvine L.H. Ong, and Anupam Sengupta. 2021. "Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements" Crystals 11, no. 1: 35. https://doi.org/10.3390/cryst11010035

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