Distinguishing Heteroaggregation from Homoaggregation in Mixed Binary Particle Suspensions by Multiangle Static and Dynamic Light Scattering

Abstract

Time-resolved multiangle light scattering is used to measure absolute heteroaggregation (heterocoagulation) rate constants in aqueous binary colloidal particle mixtures. These measurements are possible despite the simultaneous occurrence of homoaggregation (homocoagulation). The procedure can be used with static as well as with dynamic light scattering, even though the latter technique is more accurate and more sensitive. The approach exploits the differences in the form factors of the asymmetric particles dimers. Particles of unequal size are therefore needed, but the method is sensitive already to 10% difference in size. We have applied the technique for latex particles in 100-200 nm size range, where the Rayleigh-Gans-Debye approximation is accurate, and obtained the formation aggregation (coagulation) rate constants for the asymmetric dimers as a function of the ionic strength up to 300 mM.

Heteroaggregation of nanoparticles with biocolloids and geocolloids

“…Homoaggregation involves particles of the same type, while heteroaggregation occurs between particles of different types, size and properties [83]. Most nanoparticles tend to aggregate once they are hydrated, and this aggregation process is important for their sedimentation rates [14][15][16].…”

“…In addition, multiangle light-scattering techniques are capable of distinguishing homoaggregates from heteroaggregates [199]. Thus, multiangle static and dynamic light scattering have emerged as powerful tools to probe the particle aggregation processes in-situ [200,201].…”

Heteroaggregation, repeptization and stability in mixtures of oppositely charged colloids

“…Early stage fractal cluster formation was analyzed in detail in [3]. Kinetics of heteroaggregation (mainly in the early stage) also received much attention [5][6][7]. In [7] heteroaggregation versus homoaggregation was studied by varying the ionic strength.…”

“…Kinetics of heteroaggregation (mainly in the early stage) also received much attention [5][6][7]. In [7] heteroaggregation versus homoaggregation was studied by varying the ionic strength. Simulation of growth of large heteroaggregates, determination of fractal size of heteroaggregates and the effect of added electrolyte were recently presented in [4].…”

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

“…This technique is only reliable when heteroaggregation takes place. However, in general homoaggregation and heteroaggregation take place simultaneously, and the separation of both processes is nontrivial [12,13]. One way to tackle this problem is to measure an apparent aggregation rate constant in such a mixed system.…”