ABSTRACT
This chapter discusses interactions between two planar parallel walls when a fluid of spherical particles fills the slit between their surfaces. It deals with interactions like the van der Waals interaction between the two walls themselves, which may be denoted as body forces. The chapter considers the effect of ion-ion correlations and the intricate coupling between electrostatic and van der Waals interactions, including ion-wall dispersion interactions. It proposes surface forces between charged surfaces in contact with electrolytes in the Poisson-Boltzmann approximation. For a double-layer system with two surfaces at large separation from each other, the charge distribution near each surface is only slightly affected by the presence of the other surface. The chapter provides a general treatment without approximations of surface forces for fluids with spherical particles, like hard spheres or Lennard-Jones particles.
