IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Suspensions of charged colloidal particles: From the primitive model to long-time diffusion
Autor/es:
M. HEINEN; E. ALLAHYAROV; T. PALBERG; A. V. IVLEV; G. E. MORFILL; ADOLFO J. BANCHIO; GERHARD NÄGELE; H. LÖWEN
Lugar:
Ventura, California
Reunión:
Conferencia; Colloidal, Macromolecular & Polyelectrolyte Solutions: Toward Active Materials; 2014
Institución organizadora:
Gordon Research Conference
Resumen:
We investigate suspensions of charged colloidal particles in theory, simulation and experiment. Our work comprises a hierarchy of structural and dynamical phenomena with  rising levels of complexity in their theoretical description.The most fundamental description employed here is the primitive model (PM), where all ion species in suspension are treated on equal footing as non-overlapping hard spheres with Coulomb interactions. We have successfully tackled the long-standing problem of solving liquid integral equations for the pair-correlations of a PM with charged, micrometer-sized colloids and sub-nanometer sized, monovalent microions [1]. In a next step, surface chemistry is added to the PM, by solving association-dissociation rate equations for all ionic species, coupled to the liquid integral equations for the pair-correlations. In this way, we gain a parameter-free ab initio model of reentrant-solid-phase behavior of charged colloidal silica spheres in aqueous solutions with added sodium hydroxide [2]. Our PM results are compared to those from a one-component macroion ?uid (OMF) description, where the degrees of freedom of microions are integrated out and colloidal particles interact via effective potentials. Within the OMF model, we compute short-time diffusion and rheology of charged and uncharged colloidal particles, with an accurate account for hydrodynamic interactions [3]. Our mode-coupling theory results and Stokesian Dynamics simulations for long-time diffusion of charged colloids allow us to investigate the validity range of dynamic scaling with factorized time- and wavenumber dependence of the relaxation rate of density ?uctuations [4]. In an interdisciplinary collaboration, we investigate the structure and dynamics of complex (dusty) plasmas. Here, dust particles exhibit quasi undamped motion in a dilute background plasma, with screened electrostatic interactions very similar to those of charged colloidal particles. An important difference to colloidal suspensions is a violation of Newton?s third law for the dust particle interactions in a coarse-grained description, giving rise to unforeseen kinetic and structural phenomena.