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We make a comparison of a perturbation density functional (DF) theory and an integral equation (IE) theory with the results from Monte Carlo simulations for nonuniform fluids of hard spheres with one or two association sites. The DF used applies the weighting from Tarazona’s hard sphere density functional theory to Wertheim’s bulk first order perturbation theory. The IE theory is the associative form of the Henderson–Abraham–Barker (HAB) equation. We compare results from the theories with simulation results for density profiles and adsorption of one- and two-sited associating fluids against a hard, smooth wall over a range of temperatures and molecular densities. We also report fraction of monomers profiles for the DF theory and compare these against simulation results. For dimerizing fluids, the DF theory is more accurate very close to the wall, especially at higher densities, while the IE theory has more accurate peak heights and positions away from the wall, also especially at higher densities. Accuracy of the IE theory increases with an increasing degree of association. For two-sited hard spheres, the DF theory is more accurate than the IE theory at lower densities; at higher densities accuracies are similar to that of dimerizing hard spheres.

On the basis of a combination of the lattice gas and the linear elasticity theories, we argue that the major features of the intercalation isotherms can be well understood in terms of a coupling between the configurational and the structural transitions. Competitive effects of the internal and loading stresses are discussed. A simple model, operating with the hydrostatic parts of the stress and strain fields, is shown to be applicable to a quantitative description of experimental data on electrochemical intercalation into crystalline and layered host matrixes.

The role of a matrix response to a fluid insertion is analyzed in terms of a perturbation theory and Monte Carlo simulations applied to a hard sphere fluid in a slit of fluctuating density-dependent width. It is demonstrated that a coupling of the fluid-slit repulsion, spatial confinement, and the matrix dilatation acts as an effective fluid-fluid attraction, inducing a pseudocritical state with divergent linear compressibility and noncritical density fluctuations. An appropriate combination of the dilatation rate, fluid density, and the slit size leads to the fluid states with negative linear compressibility. It is shown that the switching from positive to negative compressibility is accompanied by an abrupt change in the packing mechanism.

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