This title appears in the Scientific Report :
2012
Please use the identifier:
http://dx.doi.org/10.1039/c1sm06735d in citations.
Please use the identifier: http://hdl.handle.net/2128/4627 in citations.
Dynamics of charged gibbsite platelets in the isotropic phase
Dynamics of charged gibbsite platelets in the isotropic phase
We report on depolarized and non-depolarized dynamic light scattering, static light scattering, and steady shear viscosity measurements on interacting charge-stabilized gibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average collective and (long-time) translational self-diffusion coef...
Saved in:
Personal Name(s): | Kleshchanok, D. |
---|---|
Heinen, M. / Nägele, G. / Holmqvist, P. | |
Contributing Institute: |
Weiche Materie; ICS-3 |
Published in: | Soft matter, 8 (2012) S. 1584 - 1592 |
Imprint: |
Cambridge
Royal Society of Chemistry (RSC)
2012
|
Physical Description: |
1584 - 1592 |
DOI: |
10.1039/c1sm06735d |
Document Type: |
Journal Article |
Research Program: |
BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung |
Series Title: |
Soft Matter
8 |
Subject (ZB): | |
Link: |
Get full text OpenAccess Published under German "Allianz" Licensing conditions on 2011-12-14. Available in OpenAccess from 2012-12-14 |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/4627 in citations.
We report on depolarized and non-depolarized dynamic light scattering, static light scattering, and steady shear viscosity measurements on interacting charge-stabilized gibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average collective and (long-time) translational self-diffusion coefficients, and the rotational diffusion coefficient, have been measured as functions of the platelet volume fraction phi, up to the isotropic-liquid crystal (I/LC) transition. The non-depolarized intensity autocorrelation function, measured at low scattering wavenumbers, consists of a fast and a slowly decaying mode which we interpret as the orientationally averaged collective and translational self-diffusion coefficients, respectively. Both the rotational and the long-time self-diffusion coefficients decrease very strongly, by more than two orders of magnitude, in going from the very dilute limit to the I/LC transition concentration. A similarly strong decrease, with increasing phi, is observed for the inverse zero-strain limiting steady shear viscosity. With increasing phi, increasingly strong shear-thinning is observed, accompanied by a shrinking of the low shear-rate Newtonian plateau. The measured diffusion coefficients are interpreted theoretically in terms of a simple model of effective charged spheres interacting by a screened Coulomb potential, with hydrodynamic interactions included. The disk-like particle shape, and the measured particle radius and thickness polydispersities, enter into the model calculations via the scattering amplitudes. The interaction-induced enhancement of the collective diffusion coefficient by more than a factor of 20 at larger phi is well captured in the effective sphere model, whereas the strong declines of the experimental translational and rotational self-diffusion coefficients are underestimated. |