1. Departments of Chemical Engineering and Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, Foundation for Research and Technology−Hellas (FORTH), Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10 Heraklion, Crete, Greece, and Center for Education and Research on Macromolecules (CERM), University of Liège, Sart-Tilman, B6, 4000 Liège, Belgium