Measurement of steric stabilizer barrier thickness in dispersions of poly(methyl methacrylate) in aliphatic hydrocarbon

The thickness of a surface layer of poly(12-hydroxy-stearic acid) stabilizing a dispersion of poly(methylmethacrylate) particles in aliphatic hydrocarbon has been found by a hydrodynamic technique to be 6.2 nm. However, from the point of view of steric stabilization against flocculation, the thickness of a layer of solvated unfractionated polymer may be more closely related to the dimensions of the larger molecular species present. From calculations based upon gel permeation chromatography these molecules could extend at least 15 nm from the particle surface. This prediction is in good agreement with recent determinations of the steric thickness of the layer of solvated polymer.