AbstractThe paper investigates the structure formation in thin polymer blend films. Such a control of the structure formation is of great importance in many industrial applications. In this paper we follow two different routes in order to control the surface structures. One is the creation of surface structured through a dewetting of the thin films. The dewetting is archived through a plastification of the film either annealing or by swelling in a solvent atmosphere. As a result the control of this process allows to form very small and regular structures. The second route utilizes the demixing of an strongly immiscible polymer blend during preparation and yields much less defined structures. To allow a quantitative comparison if the evolving surface structures are statistically analyzed in terms of their rms-roughness and Fourier spectrum and compared with predictions from existing growth models.