1. Institute of Organic Chemistry III/Macromolecular Chemistry; Ulm University; Albert-Einstein-Allee 11 89081 Ulm Germany
2. Department Synthesis of Macromolecules; Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
3. Institute of Physiological Chemistry; Ulm University; Albert-Einstein-Allee 11 89081 Ulm Germany
4. Department of Chemistry; University of Cambridge; Lensfield Road CB2 1EW Cambridge UK