Enhanced structural correlations accelerate diffusion in charge-stabilized colloidal suspensions

Overbeck, Ekkehard; Sinn, Christian; Watzlawek, M.

doi:10.1103/physreve.60.1936

Cited by 20 publications

(19 citation statements)

References 15 publications

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“…The coefficient a s ≈ 1.8 in the expression for the sedimentation coefficient is nearly constant. The present expressions for D r and D s have been confirmed experimentally [69,75], and we will show that they conform with existing LB and our ASD simulation data up to φ ≈ 0.35 and φ ≈ 0.1, respectively.…”

Section: Charge-stabilized Spheressupporting

confidence: 66%

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres

Banchio

Nägele

2008

The Journal of Chemical Physics

170

319

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We present a detailed study of short-time dynamic properties in concentrated suspensions of charge-stabilized and of neutral colloidal spheres. The particles in many of these systems are subject to significant many-body hydrodynamic interactions. A recently developed accelerated Stokesian Dynamics (ASD) simulation method is used to calculate hydrodynamic functions, wavenumber-dependent collective diffusion coefficients, self-diffusion and sedimentation coefficients, and high-frequency limiting viscosities. The dynamic properties are discussed in dependence on the particle concentration and salt content. Our ASD simulation results are compared with existing theoretical predictions, notably those of the renormalized density fluctuations expansion method of Beenakker and Mazur, and earlier simulation data on hard spheres. The range of applicability, and the accuracy of various theoretical expressions for short-time properties, are explored through comparison with the simulation data. We analyze in particular the validity of generalized StokesEinstein relations relating short-time diffusion properties to the high-frequency limiting viscosity, and we point to the distinctly different behavior of de-ionized charge-stabilized systems in comparison to hard spheres.

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Section: Charge-stabilized Spheressupporting

confidence: 66%

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres

Banchio

Nägele

2008

The Journal of Chemical Physics

170

319

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“…This allows the improvement of the δγ scheme by replacing the hard-sphere δγ prediction for D s by the accurate simulation value which is a less time-consuming method than the full ASD simulation of H(q). The hybrid method amounts to an upward shift of the δγ − H(q) by a small to moderately large value, since the D s of charged spheres is larger than that of neutral ones [11,21]. Even without the correction for D s , the δγ scheme is useful in detecting trends in the behavior of H(q).…”

Section: Simulation and Theorymentioning

confidence: 99%

Hydrodynamic and electrokinetic effects on the dynamics of charged colloids and macromolecules

Banchio

McPhie

Nägele

2008

J. Phys.: Condens. Matter

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Abstract. We explore dynamic processes in suspensions of charge-stabilized colloidal particles and biological macromolecules. Various short-time transport properties including diffusion functions and the high-frequency viscosity, have been calculated by means of a recently developed accelerated Stokesian Dynamics simulation tool. This has allowed us to study dense suspensions with many-body hydrodynamic interactions. The results of this study are used to explore the validity of generalized StokesEinstein relations, and the possibility of measuring self-diffusion at a finite scattering wave number. The influence of the electrolyte ion dynamics on the colloidal longtime self-diffusion in non-dilute suspensions of small colloids is determined using a many-component mode-coupling theory that accounts for the inter-ionic hydrodynamic interactions. We investigate the influence of the asymmetry in the electrolyte ion charges and mobilities on the friction experienced by the charged colloids. It is shown that these asymmetries affect the electrolyte friction significantly, and that the electrolyte friction contribution to self-diffusion decreases with increasing colloid concentration.Hydrodynamic and electrokinetic effects in charge-stabilized colloids 2

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“…(24) and (25) have recently been confirmed by lattice Boltzmann simulations, 36 DDLS, 58 and DLS. 59 It was shown that eqn. (24) applies up to f % 0.3, whereas eqn.…”

Section: Sed Scaling In Binary Hard-sphere Mixturesmentioning

confidence: 99%

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

et al. 2002

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According to the Stokes-Einstein-Debye (SED) relation, the rotational diffusion coefficient of a colloidal tracer sphere scales with the inverse of the solvent viscosity. Here we investigate the generalization of the SED relation to tracer diffusion in suspensions of neutral and charged colloidal host spheres. Rotational diffusion coefficients are measured with dynamic light scattering and phosphorescence spectroscopy, and calculated including two-and three-particle hydrodynamic interactions. We find that rotational tracer diffusion is always faster than predicted by the SED relation, except for large tracer/host size ratios l. In the case of neutral particles this observation is rationalized by introducing an apparent l-dependent slip boundary coefficient. For charged spheres at low ionic strength, large deviations from SED scaling are found due to the strongly hindered host sphere dynamics. Finally, we present some first experiments on tracer sphere diffusion in suspensions of host rods, showing that hydrodynamic hindrance by rods is much stronger than by spheres. We conclude by pointing to some interesting unresolved issues for future research. I IntroductionThe rotational diffusion coefficient of a single colloidal sphere with radius a T suspended in a solvent with shear viscosity Z 0 is given by the familiar Stokes-Einstein-Debye (SED) relationwith k B T the thermal energy and f r 0 the Stokesian friction factor. Eqn. (1) assumes that the particle is large enough for the solvent to behave as a structureless continuum with vanishing response time. Moreover, stick boundary conditions are assumed, i.e. the velocity of the fluid on the tracer surface equals that of the tracer. Eqn. (1) holds quantitatively not only for colloidal particles but,

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Enhanced structural correlations accelerate diffusion in charge-stabilized colloidal suspensions

Cited by 20 publications

References 15 publications

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres

Hydrodynamic and electrokinetic effects on the dynamics of charged colloids and macromolecules

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

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