14 Externe wissenschaftliche Einrichtungen
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/15
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Item Open Access Interfaces in fluids of charged platelike colloids(2007) Bier, Markus; Dietrich, Siegfried (Prof. Dr.)Whereas some theoretical studies of bulk fluids of charged platelike colloids -- which exhibit a rich phase behaviour including sol-gel transitions, flocculation, and liquid crystalline phases -- have been performed in the past, no theoretical investigations of inhomogeneities of such systems have been undertaken prior to this work. Within the present work, a model fluid composed of a ternary mixture of monodisperse platelike macroions and salt ions is considered. A density functional theory is developed which is able to describe the model fluid in bulk configurations, with a free interface between coexisting bulk phases, as well as in the presence of a charged substrate. The bulk phase diagrams exhibit one isotropic phase and one nematic phase separated by a first-order phase transition. The Donnan potential between coexisting phases can be expressed in terms of the particle chemical potentials obtained from bulk structure calculations. Surface phase transitions are investigated by means of an asymptotical analysis of effective interface potentials and by numerical solutions of the Euler-Lagrange equations. The effective interface potentials exhibit the same asymptotic behaviour as systems governed by non-retarded isotropic dispersion forces although the model does not include dispersion forces. Various qualitative conclusions concerning the structure of interfaces, interfacial tensions, wetting behaviour of charged substrates, as well as electrostatic properties of the model fluid are testable by experiments or computer simulations.