1. Institute of Polymer Chemistry; University of Stuttgart; Pfaffenwaldring 55 D-70569 Stuttgart Germany
2. Daimler AG; RD/EKI; Hanns-Klemm-Straße 45 D-71034 Böblingen Germany
3. Max Planck Institute for Solid State Research; Heisenbergstraße 1 D-70569 Stuttgart Germany