1. Department of Chemical Engineering and CERSIM, Laval University, Sainte-Foy, Québec, Canada G1K 7P4; Center for Education and Research on Macromolecules, University of Liège, Sart-Tilman B6, 4000 Liège, Belgium; and Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany