Despite its widely accepted importance, the exact role of water in protein adsorption is still an unresolved issue. It is generally acknowledged that hydrophobic interactions are an important factor controlling the adsorption of proteins (and other amphiphilic molecules) to various types of surfaces. However, no general consensus exists about the exact role of the hydrophobic effect in adsorption processes. Adsorption is traditionally discussed with respect to the very surface properties of a material, involving only the top layer of atoms or molecules. In this thesis we want to test the central hypothesis that a vertical chemical gradient below the  surface affects the adsorption of amphiphilic molecules such as surfactants or proteins. The vertical chemical gradients used in this thesis need to meet several requirements. First of all the thickness of the gradient has to be controllable and the specific energy of the gradient should be tunable over a reasonable range of surface free energies. In addition, the vertical structure needs to be stable over time in aqueous environments and should allow for the penetration of water into the gradient. Plasma polymerization offers the possibility to deposit films meeting these requirements. However, a precise control over film deposition must be established. [...]