This work presents experimental results on grafted polymer films. The aim was to understand transition processes in grafted polymer films regarding their structure and chain mechanics. For such purpose structural attributes of grafted polymer films were related to mechanical attributes. First the fundamental background, which is needed to analyze and understand experimental data, is pictured. This includes also new approaches for scattering data analysis. Experimental studies were focused on two different kinds of polymer film systems were investigated. Endgrafted poly-mehtyl-methacrylate (PMMA) brush films were investigated regarding their collapse - swelling transition on the solvent quality. It was observed that attractive interactions in the brush decreased for theta solvent conditions. For grafted to polystyrene (PS)/poly-vinyl-methyl-ether (PVME) blend films was concluded that the grafted polymer chains need an adequate degree of entropical freedom to undergo phase separations. Mechanical surface stress experiments made the understanding of the observed phase separation mechanisms possible.