1. Institute of Polymers; Bulgarian Academy of Sciences; Acad. G. Bonchev Str., bl. 103-A Sofia 1113 Bulgaria
2. Leibniz-Institut für Polymerforschung Dresden; Hohe Str. 6 01109 Dresden Germany
3. Technische Universität Dresden; 01062 Dresden Germany
4. Theoretical and Physical Chemistry Institute; National Hellenic Research Foundation; 48 Vassileos Constantinou Ave 116 35 Athens Greece