Influence of the Counterion Nature on the Stability Sequence of Hydrophobic Latex Particles.

The aggregation kinetics of negatively charged polystyrene latex particles in the presence of monovalent electrolytes have been investigated. The inferred coagulation critical concentrations were compared to establish the stability sequence. With the same representative co-ions, this sequence is reversed when using kosmotrope sodium and chaotrope potassium cations.

Influence of Co-Ion Nature on the Gelation Kinetics of Colloidal Silica Suspensions.

The influence of the nature of three representative monovalent co-ions on the gelation kinetics of Ludox suspensions has been investigated. At a given Ludox volume fraction and for the same concentration of potassium salt, the gelation time is longer as the studied anion presents a more pronounced kosmotrope character. As the screening of the silica surface charge is similar since the same cationic counterion is taken, these results highlight the unexpected role played by hydration effects imparted by the co-ions when particles are pushed together as gelation proceeds.