1. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
2. Department of Chemistry, University of California, Berkeley, California 94720, United States
3. Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
4. CNRS, Ingenierie des Materiaux Polymeres, Univ Lyon, Universite Lyon 1, UMR 5223, F-69003 Lyon, France
5. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States