Dispersion properties of an alumina nanopowder using molecular, polyelectrolyte, and steric stabilization

A commercial alumina nanopowder was characterized and its dispersion was studied using electrostatic, electrosteric, and steric surfactants. Citric acid was used as the electrostatic dispersant, ammonium polymethacrylic acid (Darvan C) as the electrosteric dispersant, and Hypermer KD-1 in a-terpineol as a purely steric system. Phase stability in water was examined by X-ray diffraction, and the surface chemistry was characterized by zeta potential and isoelectric points. Rheology measurements were used to study the impact of each dispersant type on maximum solids loading, with the maximum loading being achieved for the polyelectrolyte dispersant. Differences in maximum solids loading are related to the excluded volume of the particle separation distance induced by each stabilizing interaction.