Enhanced steric stabilization

Abstract An extensive series of experiments has previously demonstrated that for model sterically stabilized dispersions, 0-solvents for the stabilizing chains in free solution represent the limit of colloid stability. It has now been shown that by anchoring the stabilizing chains to the particle surfaces at many points along the chains, the pattern of flocculation behavior may be profoundly altered. Polystyrene latices stabilized by poly(ethylene oxide) have been prepared that are stable in dispersion media with solvency for the stabilizing moieties markedly worse than 0-solvents for the chains in free solution. Multipoint anchoring in these systems results from the hydrogen bonding between the ether oxygens of the stabilizer and surface carboxylic acid groups. The enhancement of steric stabilization is a function of the pH and the molecular weight of the stabilizing chains. It originates in the perturbation of the conformation of the stabilizing macromolecules that renders the free solution properties of the chains no longer relevant.