1. Makromolekulare Chemie I, Makromolekulare Chemie II, and Experimentalphysik and Bayreuther Institut für Makromolekülforschung, Universität Bayreuth, D-95440 Bayreuth, Germany, Zentrale Forschung/Informationstechnologie, Bayer AG, 51368 Leverkusen, Germany and Materials Department, University of California at Santa Barbara, Santa Barbara, California, 93106