ABSTRACT
The theoretical treatment of the interparticle forces characterizing the stability of solid dispersions is well developed. This chapter describes a new technique utilizing the osmotic pressure of concentrated particle dispersions in a frozen solvent. In the freezing process two microdomains are formed within the frozen dispersion: one, the pure oil solvent that is selectively solidified, the other, a concentrated "liquid" dispersion of particles in oil which separates when the solvent freezes. Combined with small-angle neutron scattering (SANS) measurements to determine the interparticle separation, the osmotic pressure provides a measure of the interparticle repulsion forces between the adsorbed monolayers on a 3-D configuration of particles. Scanning electron microscopy was also employed to examine the configuration adopted by the microdomains within a frozen dispersion of CaCO3particles. The SANS behavior of the corresponding CaCO3 particle system shows a similar response to pressure and temperature on solidification of the dispersion.
