The effect of adsorption on the van der waals interaction of spherical colloidal particles
1961; Academic Press; Volume: 16; Issue: 1 Linguagem: Inglês
10.1016/0095-8522(61)90057-5
ISSN1878-321X
Autores Tópico(s)Electrostatics and Colloid Interactions
ResumoAbstract A general formula has been derived for the interaction of spherical particles surrounded by any number of concentric shells of adsorbed material. The net interaction energy seems to be invariably negative (attraction) regardless of the magnitude of the van der Waals' constants of the materials comprising the particle, medium, and adsorbed substances. This result is demonstrated for one and for two adsorbed layers (i.e., a single layer of oriented amphipathic molecules), although it was not found feasible to develop a general proof. The interaction energy of solvated particles may be reduced by factors of the order of 5 to 50 compared to that of unsolvated particles. However, if current estimates of the magnitude of the van der Waals' constants are correct, flocculation can be inhibited by solvation alone only for small particles ( ca. 20 A.). Stabilization is most effective when the van der Waals' constant for the adsorbed material is either greater or less than the van der Waals' constants for both particle and medium.
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