1. Functional Polymers Group and Institute of Polymer Technology, and Analytical Chemistry, University of Wuppertal, Gaussstrasse 20, D-42097 Wuppertal, Germany, Institute of Physical Chemistry, University of Cologne, Luxemburgerstrasse 116, D-50939 Cologne, Germany, and Dutch Polymer Institute (DPI), P.O.Box 902, 5600 AX Eindhoven, The Netherlands