Journal Article

FZJ-2019-05270

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Coupling of long-wavelength density fluctuations to orientations in cellulose nanocrystal suspensions under external fields

Kang, K. (Corresponding author)FZJ* ; Bertsch, P. ; Fischer, P.

2019
Inst. Woodbury, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/23515  doi:10.1103/PhysRevE.100.052606

Abstract: Motivated by the development of cellulose-based functional materials, we investigate the microscopic dynamics of suspensions of cellulose nanocrystals (CNC) at different ionic strengths, both in the absence and presence of AC electric fields, and for various temperatures. A concentration of 5wt% of the CNCs is chosen, for which the dispersions are in the full chiral-nematic state at low ionic strengths. Dynamic light scattering is used to characterize the wavevector-dependent decay rates of number-density fluctuations. Contrary to an isotropic suspension, the dispersion relations (the wavevector dependence of the correlation-function decay rates) as obtained by means of depolarized light scattering are found to exhibit anomalous behaviour. The dispersion relations, both without and with an external field, exhibit minima at small wavevectors, which is attributed to coupling of translational motion to the orientation of the CNCs, shown in the chiral-nematic state. The location of the minima is found to weakly depend on ionic strength, and shifts significantly towards larger wavevectors upon applying an external electric field for sufficiently high ionic strengths. Finally, preliminary results are presented for smaller length-scale density fluctuations (at larger wavevectors) as a function of temperature, revealing the anisotropic mobilities in the chiral-nematic state of CNCs.

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Contributing Institute(s):

1. Weiche Materie (ICS-3)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)

Appears in the scientific report 2019

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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