Related Experiment Video
Updated: Aug 23, 2026

Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
Heteroaggregation, repeptization and stability in mixtures of oppositely charged colloids
M Raşa1, A P Philipse, J D Meeldijk
1Van 't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.rasa@chem.uu.nl
Abstract:
We report a study of mixtures of initially oppositely charged particles with similar size. Dispersions of silica spheres (negatively charged) and alumina-coated silica spheres (positively charged) at low ionic strength, mixed at various volume ratios, exhibited a surprising stability up to compositions of 50% negative colloids as well as spontaneous repeptization of particles from the early-stage formed aggregates. The other mixtures were found to contain large heteroaggregates, which were imaged using cryogenic electron microscopy. Electrophoretic mobility, electrical conductivity, static and dynamic light scattering and sedimentation were studied as a function of volume fraction of the mixed dispersions to investigate particle interactions and elucidate the repeptization phenomenon.
Related Concept Videos
The Colloidal State
Colloidal precipitates
Colloids
Coagulation
Colloids and Suspensions
Solubility
A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
In a solution, the solute particles (molecules, atoms, and/or ions)...

