SELF-ASSEMBLY AND ORDERING OF ELECTROSTATICALLY STABILIZED SILICA SUSPENSIONS

We use optical attenuation spectral measurements and diffraction measurements to examine the structural evolution of aqueous suspensions of negatively charged colloidal silica particles in thin quartz cells. The ionic strength in the suspension is monotonically decreased in time by ion-exchange resin. At high ionic strengths, two-dimensional hexagonal order nucleates near the surface of the cell walls, while the regions away from the walls show liquid-like order. At lower ionic strengths, regions near the wall show three-dimensional order, while the interior region shows two-dimensional crystalline order. At the lowest ionic strengths, the entire suspension shows three-dimensional crystalline order. © 1992.