THE EFFECTS OF SOLVENCY ON THE STRUCTURE OF AN ADSORBED POLYMER LAYER AND DISPERSION STABILITY

Small-angle neutron scattering (SANS) and photon correlation spectroscopy (PCS) have been used to determine the volume fraction profiles, adsorbed amounts and hydrodynamic thickness of poly (vinyl alcohol-co-acetate) and poly (ethylene oxide) adsorbed on polystyrene latex from water. The effects of solvency on the structure of the adsorbed layer and the stability of the dispersions have been investigated by varying temperature in the presence of electrolyte. The results show that the thickness of the layer contracts on approach to flocculation and that the volume fraction of segments near the interface increases together with a concomitant increase in the adsorbed amount. The profiles are used to calculate the steric barrier due to interpenetration and the results are discussed in terms of dispersion stability. © 1990.