Equilibrium interaction between adsorbed polymer layers

We discuss the force between two surfaces coated with adsorbed polymer layers in thermodynamic equilibrium with a polymer solution. We use a mean-field theory that explicitly takes into account the loops and tails structure of the adsorbed polymer layers. The force has a non-monotonic variation with distance: it is attractive at short distances where the loops dominate and where bridging is important and it is repulsive at large distances where the tails dominate.