Confined chains with specific interactions, bridges, loops and osmosis

We describe the macroscopic behavior of Gaussian chains confined between impenetrable surfaces and having ends interacting with the surfaces taking into account all multiple reflections from the two surfaces. The statistics of chains with the absorbing boundary conditions are used and proper interactions between the chain ends and the surfaces are included. We determine and study the forces in terms of the characteristics of the surface interactions and the ratio d/S of the distance of the surfaces to the mean radius of gyration of the chain. Suitable choices of the parameters of the model reproduce many features observed experimentally for homopolymers and block copolymers.