Dewetting of confined polymer films:: an X-ray and neutron scattering study

The dewetting behavior of thin, deuterated polystyrene (dPS) layers on silicon surfaces is investigated. The surface topographics thus produced are investigated with scanning force microscopy and with grazing incidence small angle scattering. Neutrons and X-rays interact differently with this system, producing a reverse of the scattering contrast in the investigated system dPS-Si. For samples annealed above their glass transition temperature a difference in the evolved surface structures is detected as compared with samples stored under toluene vapor. Confined thin films, with a thickness below one-third of the radius of gyration of the unperturbed molecule l < R-g/3, dewet irrespective of the applied sample treatment. Thin, but non-confined samples stay stable during annealing, whereas they dewet in a toluene vapor atmosphere.