1. Department of Physics, University of Ioannina, 45110 Ioannina, Greece
2. Department of Chemistry, University of Massachusetts Lowell, Lowell, Massachusetts 01854, United States
3. Institut für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany
4. Max Planck Institute for Polymer Research, 55128 Mainz, Germany
5. Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece