A simple modified Poisson-Boltzmann formalism, which accounts also for those interactions between electrolyte ions and colloidal particles not included in the mean potential, is used to calculate the force between two parallel plates. It is shown that the short-range interactions between ions and plates, such as those due to the change in the hydration free energy of a structure-making/breaking ion that approaches the interface, affect the double layer interaction at large separations through the modification of the surface potential and surface charge density. While at short separations (below the range of the short-range ion-hydration forces) the interaction can be attractive, at larger separations the interaction is always repulsive, as in the traditional theory. When the long-range van der Waals interactions between the ions and the system (ion-dispersion interactions) are accounted for in the modified Poisson-Boltzmann approach, an attractive force between plates can be generated. At sufficiently large separations, this attraction can become even stronger than the traditional van der Waals attraction between plates of finite thickness, thus generating a dominant long-range 'double layer attraction'. At small plate separations, the attraction generated by the ion-dispersion forces combined with the electrostatic repulsion due to the double layers overlap can lead to a variety of interactions, from a weak attraction (which is typically by at least one order of magnitude smaller than the traditional van der Waals attraction between plates) to a strong double layer repulsion (for sufficiently large surface charges). Both types of ion interactions (long-range van der Waals or short-range ionic hydration) strongly affect the magnitude of the double layer interaction, and can account for the specific ion effects observed experimentally. However, they do not affect qualitatively the traditional theory of the colloid stability, which predicts that the colloid is stable when there is a sufficiently large charge on the surface, and coagulates when the van der Waals interactions between two colloidal particles dominate. The only qualitative difference found when the ion-dispersion interactions were incorporated into the traditional double layer theory was the emergence of a 'double layer attraction' at very large separations, which, however, does not affect much the stability of colloids.

中文翻译：

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通过离子水合产生的特定离子效应：II。双层交互。

一个简单的修正的泊松-玻尔兹曼形式主义，也解释了电解质离子和平均电位中不包括的胶体颗粒之间的相互作用，用于计算两个平行板之间的力。结果表明，离子和板之间的短程相互作用（例如由于结构/断裂离子接近界面的水合自由能的变化所引起的相互作用）通过修饰而影响了大间距下的双层相互作用。表面电位和表面电荷密度的关系。在短距离分离时（低于短距离离子水合作用力的范围），相互作用可能很有吸引力，而在较大分离距离时，相互作用始终是排斥性的，如传统理论中所述。在改良的Poisson-Boltzmann方法中考虑到离子与系统之间的范德华相互作用（离子分散相互作用）时，可在板之间产生吸引力。在足够大的间距下，此吸引力可能会变得比有限厚度的板之间的传统范德华力更强，从而产生占优势的远距离“双层吸引力”。在小板间距下，由于双层重叠而导致的离子分散力与静电排斥相结合而产生的吸引力会导致各种相互作用，从弱的吸引力（通常比板之间的传统范德华力小至少一个数量级）到强的双层排斥（对于足够大的表面电荷）。两种类型的离子相互作用（长程范德华力或短程离子水合作用）都强烈影响双层相互作用的程度，并且可以解释实验观察到的特定离子效应。但是，它们并没有在质量上影响传统的胶体稳定性理论，该理论认为，当表面上有足够大的电荷时，胶体是稳定的，而当两个胶体颗粒之间的范德华相互作用占主导时，胶体就会凝结。