Dependence of solvation on particle shape

Abstract

The relationships which exist between the solvation and shape of colloid particles, as well as between solvation and viscosity, are discussed. From the most important experiments on these subjects the following conclusions may be drawn. Solvation is dependent on the size and shape of the particles and on the chemical relationship of the dispersion medium to the dispersed portion. True or chemical solvation is generally very small and there is no reason to speak of a thick and tightly bound solvent layer. The solvation of compactly formed particles of spherocolloids is greater, the smaller the particles (all other conditions being equal). Solvation is greater, the more loosely the particles are formed (for dispersion mediums having similar chemical properties and for similar dispersed or dissolved substances). Solvation increases when a corpuscular particle is transformed into a rodlike or threadlike particle; the viscosity also increases; if the threads are further broken down into smaller fragments, then the viscosity decreases, but a further increase in the chemical solvationis supposed to occur. The stability of many lyophilic sols, especially the proteins, depends very little on the solvation; it is mainly dependent on the chemical characteristics of the atomic groups which are found on the surfaces of the particles; the least stability is found for surfaces which contain heteropolar groups—that is, surfaces which have the same number of positive and negative ions.

The Binding of Anions by Lysozyme, Calf Thymus Histone Sulphate, and Protamine Sulphate

“…The solvation mantle which exists about ions in solution, protein or otherwise ( 5 , 9, 10,11,14), is particularly evident for cations (2,21). Accordingly, around the strongly positively charged centers of lysozyme, histone, and protamine there is a sheath of solvent n~olecules partially iillmobilized and orientated by the strong inhomogeneous local field.…”