1. Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
2. Institut für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany.
3. Department of Physics, University of Ioannina, 45110 Ioannina, Greece.
4. University Research Center of Ioannina (URCI) - Institute of Materials Science and Computing, 45110 Ioannina, Greece.