1. Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Golm, Germany, Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, 12489 Berlin, Germany, Fraunhofer Institute for Applied Polymer Research, Geiselbergstrasse 69, 14476 Golm, Germany, Institute of Physics, University of Potsdam, D-14415 Potsdam, Germany, and Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany