Interlayer repulsion forces

The oscillating hydration force is superimposed on a longer range repulsive force between the layers, which is predicted to be an osmotic force from the diffuse doublelayer theory (but may still contain a hydration component). Thus, as Figure 8.16 shows, closer separations between the silicate sheets result in the oscillating interlayer force becoming more repulsive on average. 

For neutral bilayers, there are no long-range doublelayer forces which, coupled with the van der Waals attraction, could explain the stability of the lamellar structure. At small separations, the required repulsion is provided by the hydration force, which was investigated both experimentally6-8 and theoretically.9,10 However, it was experimentally observed that the lipid bilayers could be swollen in water up to very large interlayer distances,11 where the short-range exponential hydration repulsion becomes negligible. 

In DLVO theory, the secondary minimum can only be created by the van der Waals force, which is essentially independent of the salt concentration across the concentration range 0.001 M < c < 0.1 M. This force has to be balanced with a force that decays exponentially as a function of k, which means that it decays by a factor exp(-10) across this range. The unhappy consequence of this prediction is that the position of the secondary minimum, and therefore the interlayer d value, varies very rapidly as a function of k, in contradiction to the experimental results. A further unhappy consequence of this balance is that it always produces a primary minimum much deeper than the secondary minimum. The full, standard DLVO thermodynamic potential energy curve, which also includes a very-short-range Bom repulsion, is shown in Figure 1.13 [23], It is therefore a definite prediction of DLVO theory that charge-stabilized colloids can only be kinetically, as opposed to thermodynamically, stable. The theory does not mean anything at all if we cannot identify the crystalline... 

Surface forces also include electrostatic interaction forces arising from the overlap of the double layers (DL) of a particle and a bubble, which usually have equal charges (Huddleston Smith 1975), i.e., the electrostatic component of the disjoining pressure of an interlayer between them (Derjaguin 1934), which may be positive. In the case of large particles, the positive disjoining pressure of the double layer is overcome by an inertia impact on the bubble surface. The small particles do not undergo such an impact the approach occurs in an inertialess way and can be hampered by electrostatic repulsion (second peculiarity). 

The interaction forces (attraction or repulsion) depend not only on the properties of the contiguous bodies and the interlayer separating these bodies, but also on the external compressive force. This force determines the width of the gap between the bodies. If the compressive force does not exceed F ax... 

The different layer-interlayer-layer sequences that are possible in the chlorite structure create varying amounts of cation-cation repulsion and cation-anion attraction as a result of the different superpositions of sheets. Bailey and Brown [1962] and Shirozu and Bailey [1965] have attempted to explain the observed relative abundances of the chlorite structural types according to the relative stabilities indicated by these interatomic forces. Repulsion between the superposed interlayer and tetrahedral cations in the la and Ila structural units is considered the most important single factor in reducing the stability of these two unit types relative to the lb and lib units. Three other factors considered are ... 

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