1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022, P. R. China
2. School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
3. BASF Polyurethane Specialties (China) Co. Ltd., 300 Jiang Xin Sha Road, Pudong
District, Shanghai 200137, P. R. China
4. Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, P. R. China