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Abstract It had previously been found in this laboratory that flexible polymer molecules adsorbed at colloidal particles most likely extend with many segments into the interior of the surrounding medium. This led one to expect a possible “steric protection” of colloidal particles by adsorption of flexible polymers of sufficiently high molecular weight since the merely slight interpenetration of polymer chains protruding from two colliding particles should keep them at distances too large to give a van der Waals interaction energy sufficient for coherence. This new type of stabilization was now proved using gold hydrosols as test systems and polyethylene glycols as adsorptives. The stabilization was found to increase with polymer concentration and, particularly, with the molecular weight of the polymer. In analogy with the previous finding, that the adsorption equilibrium is being approached very slowly if the molecular weight of the polymer exceeds several thousand, it was found that the degree of stabilization achieved by addition of polymer to the gold sols increases with the time elapsed before the subsequent addition of coagulating electrolyte. This increase is particularly strong during the first hour following addition of the polymer. The potential significance of the results for stabilization of organosols is discussed.
Heller et al. (Tue,) studied this question.