1. Department
of Materials Science and Engineering, College of Engineering, Key
Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing 100871, China
2. Fujian
Key Laboratory of Polymer Materials, College of Materials Science
and Engineering, Fujian Normal University, Fuzhou 350007, China
3. Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
4. Department
of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
5. Department
of Physics, Chinese University of Hong Kong, New Territories, Hong Kong, China