Dispersion-driven morphology of mechanically confined polymer films

To probe the effects of mechanical confinement on freely standing polystyre ne (PS) films, we have symmetrically capped freely standing PS films by thi n, solid layers. Annealing of the trilayer films produces a novel lateral m orphology which is driven by the dispersion force between the capping layer s. A simple model is presented which describes the scaling behavior of the morphology with the layer thicknesses. The same morphology is observed for freely standing and supported films in eight different systems. We also dem onstrate reversibility of the morphology by manipulation of the dispersion force. [S0031-9007(99)08501-4].