1. Department of Chemical Engineering, University of Patras and ICE/HT-FORTH, GR-26500 Patras, Greece, Chemistry Department, Heriot-Watt University Edinburgh, EH14 4AS, United Kingdom, and Laboratoire de Physique des Polymères, CP223, Université Libre de Bruxelles, Boulevard de Triomphe, B-1050 Bruxelles, Belgique