1. Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 P. R. China
2. University of Science and Technology of China Hefei 230026 P. R. China
3. Jilin Biomedical Polymers Engineering Laboratory Changchun 130022 P. R. China
4. College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China