1. Department of Polymer Science, University of Akron, Akron, Ohio 44325, United States
2. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
3. Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
4. Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg 199004, Russia