Self-organized structures at the surface of thin polymer films

When thin layers of polymer solutions dry by solvent evaporation and/or heating from below, the layers can become hydrodynamically instable. As a result various surface structures occur. A great pattern manifold of such structures has been found. By self-organization small surface motions caused by surface tension differences can be amplified, when the ratio of the driving forces to the damping ones characterized by the Marangoni-number exceeds a critical value. Besides greater and hierarchic subdivided cell patterns, periodic line structures with peak-valley-differences of down to 1 nm have been found in the solidified layers. The surface profiles (3D- and line profiles) have been measured by means of a microscope interferometer.