1. Department of materials, University of Science and Technology Beijing, Beijing, P. R. China
2. Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, P. R. China
3. Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing, P.R. China
4. Beijing Key Laboratory of Liquid Crystal Materials Analysis and Application Technology, Beijing Bayi Space Liquid Crystal Material Technology Company, Beijing, P. R. China
5. Department of Chemistry, Dalian Medical University, Dalian, P. R. China