Electrohydrodynamic convection instabilities observed in suspensions of cellulose nanocrystals.

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Frka-Petesic, Bruno 
Jean, Bruno 
Heux, Laurent 

UNLABELLED: Cellulose nanocrystals are slender, negatively charged nanoparticles that spontaneously form a cholesteric liquid crystal in aqueous suspension above a critical concentration. When they are suspended in apolar solvents such as toluene using surfactants, the application of an AC electric field leads to the reorientation and then distortion of the cholesteric order until the cholesteric structure completely unwinds into a nematic-like order, typically above 0.4-0.6 kV/cm at 1kHz. In this work, we show that at much higher electric fields (≥ 4.6 kV/cm at 1 kHz) the sample develops a periodic pattern that varies with the field amplitude. We ascribed this pattern to electrohydrodynamic convection instabilities. These instabilities usually present complex regimes varying with the field, the voltage, the frequency and the geometry. However, the typical geometry where these instabilities were most documented across the literature differs from the geometry used in this work. This work concludes with possible future experimental investigations to clarify the exact regime of instability responsible for these observations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10570-023-05391-6.

Cellulose nanocrystal, Cholesteric, Colloidal liquid crystal, Electroconvection
Journal Title
Cellulose (Lond)
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Springer Science and Business Media LLC
European Commission Horizon 2020 (H2020) ERC (963872)
European Commission Horizon 2020 (H2020) ERC (101001637)
Engineering and Physical Sciences Research Council (EP/W031019/1)
ANR (BIOSELF: ANR-08-NANO-0037), the European Cooperation in Science and Technology Action for travel grant (COST-STSM-FP1205-30247), the ERC (CelluNANo: ERC-2020-POC 963872, BiTe: ERC-2020-COG-101001637), the EPSRC (VALUED: EP/W031019/1) and the SKCM2 Hiroshima University WPI.