This title appears in the Scientific Report :
2014
Please use the identifier:
http://dx.doi.org/10.1039/c3sm52277f in citations.
Please use the identifier: http://hdl.handle.net/2128/5945 in citations.
An electric-field induced dynamical state in dispersions of charged colloidal rods
An electric-field induced dynamical state in dispersions of charged colloidal rods
The response of concentrated dispersions of charged colloids to low-frequency electric fields is governed by field-induced inter-colloidal interactions resulting from the polarization of electric double layers and the layer of condensed ions, association and dissociation of condensed ions, as well a...
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Personal Name(s): | Dhont, Jan K.G. (Corresponding author) |
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Kang, Kyongok | |
Contributing Institute: |
Weiche Materie; ICS-3 |
Published in: | Soft matter, 10 (2014) 12, S. 1987-2007 |
Imprint: |
Cambridge
Royal Society of Chemistry (RSC)
2014
|
DOI: |
10.1039/c3sm52277f |
Document Type: |
Journal Article |
Research Program: |
Soft Matter Composites |
Link: |
OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/5945 in citations.
The response of concentrated dispersions of charged colloids to low-frequency electric fields is governed by field-induced inter-colloidal interactions resulting from the polarization of electric double layers and the layer of condensed ions, association and dissociation of condensed ions, as well as hydrodynamic interactions through field-induced electro-osmotic flow. The phases and states that can be formed by such field-induced interactions are an essentially unexplored field of research. Experiments on concentrated suspensions of rod-like colloids (fd-virus particles), within the isotropic–nematic phase coexistence region, showed that a number of phases/states are induced, depending on the field amplitude and frequency [Soft Matter, 2010, 6, 273]. In particular, a dynamical state is found where nematic domains form and melt on a time scale of the order of seconds. We discuss the microscopic origin of this dynamical state, which is attributed to the cyclic, electric-field induced dissociation and association of condensed ions. A semi-quantitative theory is presented for the dynamics of melting and formation of nematic domains, including a model for the field-induced dissociation/association of condensed ions. The resulting equation of motion for the orientational order parameter is solved numerically for parameters complying with the fd-virus system. A limit-cycle is found, with a cycling-time that diverges at the transition line in the field-amplitude versus frequency plane where the dynamical state first appears, in accord with experimental findings. |