1. Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
2. Department
of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396, United States
3. Max-Planck Institute for Polymer Research, 55128 Mainz, Germany
4. Department
of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
5. Department
of Physics, Zhejiang Sci-Tech University, Hangzhou 3110018, China
6. Department
of Applied Chemistry, National Chiao Tung University, 1001 Ta Hsueh
Road, Hsin-Chu 30049, Taiwan