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Elastic flow instabilities and macroscopic textures in graphene oxide lyotropic liquid crystals

DOI: 10.1038/s41699-020-00193-x DOI Help

Authors: Jacek K. Wychowaniec (The University of Manchester; University College Dublin) , Maria Iliut (The University of Manchester) , Bartłomiej Borek (RHL-SERVICE, ul) , Christopher Muryn (The University of Manchester) , Oleksandr O. Mykhaylyk (The University of Sheffield) , Steve Edmondson (The University of Manchester) , Aravind Vijayaraghavan (The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Npj 2d Materials And Applications , VOL 5

State: Published (Approved)
Published: January 2021
Diamond Proposal Number(s): 15478 , 14948 , 12950

Open Access Open Access

Abstract: Graphene oxide (GO) forms a well-aligned lyotropic liquid crystal (LC) phase in aqueous dispersions at relatively low concentrations. Under a remarkably wide range of shear rates, we report hitherto unobserved shear-induced polarized light image patterns, a Maltese cross combined with shear banding, recorded in real time and in situ during rheological measurements. This is shown to be a result of elastic flow instabilities that manifest as a helical flow in alternating bands of left- and right-handed helices, arising from a combination of shear flow and Taylor-type vortex flow. The instability is observed for LCs formed from large aspect ratio GO particles owing to their unique viscoelastic properties, but not for smaller aspect ratio particles. This phenomenon coincides with rheopecty and anomalous small-angle X-ray scattering patterns under shear flow, which confirm the instabilities. The results presented here could lead to advanced control over macroscopic periodic alignment in technologically relevant dispersions of two-dimensional material particles.

Journal Keywords: Liquid crystals; Optical properties and devices

Subject Areas: Materials

Instruments: I22-Small angle scattering & Diffraction

Added On: 20/01/2021 13:22


Discipline Tags:

Physics Materials Science

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)