Diffusion of charged colloidal particles at low volume fraction: Theoretical model and light scattering experiments

Abstract

An appropriate mean force potential was utilized in Felderhof's Theory to derive simple analytical expressions for the concentration dependence of the collective and short time self diffusion coefficients, as well as for the sedimentation velocity of charged spherical particles. It is demonstrated theoretically that the osmotic viriat and the Oseen hydrodynamic terms play a dominant role. To check the theoretical model, the dependence of the collective diffusion coefficient on the volume fraction of latex particles was experimentally studied. Dynamic light scattering was used at several different concentrations of electrolyte. It turns out that our experimental results, as well as the results of other authors, are in very good agreement with the proposed theoretical model. The results show that the increase of the electrolyte concentration leads to increase of the particle charge, but almost does not change the particle surface potential. A minimum in the dependence of the diffusion coefficient of a single particle on the ionic strength was also obtained.

Digital Fourier microscopy for soft matter dynamics

“…As it can be appreciated in Fig. 11, SPT does not provide evidence that the sample behaves differently from a suspension of hard-spheres for which it is expected that [72]. This example shows the high potential of DFM methods in crowded environments, where tracking becomes extremely difficult if not impossible.…”

Particle Characterization Using Multiple Scattering Decorrelation Methods. Part 1: Standard Latex Particles

“…Even if this picture is regarded as being too simple [27,28], the general trend can be well reproduced. In order to account for this effect, we choose kR b 4 for our suspensions, as in this regime electroviscous effects are expected to vanish [29]. Up to this point, the colloidal particles were assumed to be rigid spheres without internal structure.…”

Interparticle potential and sedimentation of monodisperse colloid system

“…and neglecting van der Waals attraction (Petsev and Denkov, 1992;Nagele, 1996). Adopting a mean force repulsive potential, Petsev and Denkov (1992) derived a simple analytical formula for the sedimentation coefficient.…”

“…Adopting a mean force repulsive potential, Petsev and Denkov (1992) derived a simple analytical formula for the sedimentation coefficient. We can easily find that the sedimentation coefficient derived from their formula (Petsev and Denkov, 1992, Eq.…”