1. Contribution from the Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Institute Charles Sadron, 6 Rue Boussingault, Strasbourg 67083, France