1. Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, D-04103 Leipzig, Johannisallee 29, Germany, Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan, Max-Plank-Institut für Polymerforschung, D-55128 Mainz, Ackermannweg 10, Germany, and Chair of Physical Chemistry, University of Sofia, 1 J. Bourchier Boulevard, BG-1126, Sofia, Bulgaria