TY  - JOUR
AU  - Dhont, Jan K.G.
AU  - Kang, Kyongok
TI  - An electric-field induced dynamical state in dispersions of charged colloidal rods
JO  - Soft matter
VL  - 10
IS  - 12
SN  - 1744-6848
CY  - Cambridge
PB  - Royal Society of Chemistry (RSC)
M1  - FZJ-2014-01416
SP  - 1987-2007
PY  - 2014
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000332463300015
DO  - DOI:10.1039/c3sm52277f
UR  - https://juser.fz-juelich.de/record/151478
ER  -