Absolute Heteroaggregation Rate Constants by Multiangle Static and Dynamic Light Scattering

Abstract

The analysis of early-stage heteroaggregation (or heterocoagulation) in binary colloidal systems composed of oppositely charged latex particles of different size in the submicrometer size range with multiangle static and dynamic light scattering is presented. The solution conditions were adjusted to exclude any significant homoaggregation. The apparent rate obtained from static light scattering mostly strongly decreases with increasing scattering angle regardless of the number fractions, while the rate from dynamic light scattering varies in a more complicated manner. The light scattering data could be interpreted quantitatively on the basis of the Rayleigh-Gans-Debye approximation. The values of absolute heteroaggregation rate constants were found to be the same within experimental error when evaluated from static or dynamic light scattering, and they were independent of the mixing ratio. The average hydrodynamic radius of the doublet obtained from the dynamic light scattering was in good agreement with theoretical estimates based on an exact hydrodynamic treatment at low Reynolds numbers. A simple formula is proposed to estimate the hydrodynamic radius of the asymmetric particle doublet, and this formula is shown to agree well with experimental data and with theory. The new conclusion from this study is that multiangle dynamic light scattering represents the method of choice for the determination of absolute heteroaggregation rate constants. Y (20)

Assessing the colloidal properties of engineered nanoparticles in water: case studies from fullerene C60 nanoparticles and carbon nanotubes

“…The frequency of homoaggregation and heteroaggregation will depend on the particle concentrations, physical and chemical properties of the particles, and solution chemistry. [30][31][32][33] In natural aquatic systems, the fate of ENPs is more likely to be controlled by heteroaggregation between ENPs and naturally occurring colloidal particles because the concentration of naturally occurring colloids will greatly exceed that of ENPs. Nevertheless, homoaggregation is a suitable starting point for investigating the colloidal stability of ENPs because a singlecomponent suspension is a much simpler system to study systematically in the laboratory and to understand conceptually.…”

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Electrostatic heteroaggregation regimes in colloidal suspensions

“…Particularly, the dimer formation process should depend on all three possible monomer-monomer reactions, i.e., A-A, B-B and A-B. Each reaction is characterized by an absolute aggregation rate constant, namely, the absolute homoaggregation rate constants k AA and k BB , and the absolute heteroaggregation rate constant k AB [30].…”

“…Heteroaggregation processes arising in aqueous suspensions of colloidal particles with opposite charge have been monitored experimentally by means a large variety of experimental techniques such as static and dynamic light-scattering [57][58][59][60][61], multiple-angle lightscattering [30,61,62] and single-cluster light-scattering [63]. While all these techniques can be used to obtain aggregation rate constants, only SCLS provides additional information about the detailed cluster-size distribution.…”

Stimulus-Responsive Heteroaggregation of Colloidal Dispersions: Reversible Systems and Composite Materials

“…Time-resolved light scattering techniques, either static light scattering (SLS) or dynamic light scattering (DLS), are used to measure the heteroaggreagtion rate constant especially at early stage of aggregation [8]. The Rayleigh-Debye-Gans (RDG) approximation is usually applied to calculate the rate constant from light scattering.…”