1. Department of Chemistry & Biochemistry, Department of Materials, and Materials Research Laboratory, University of California, Santa Barbara, California 93106, and Laboratoire des Matériaux Polymères et Biomatériaux (LMPB/IMP-UMR CNRS 5223), Université Claude Bernard Lyon 1, 15 Boulevard Latarjet, 69622 Villeurbanne Cedex, France