1. College of Polymer Science and EngineeringQingdao University of Science and Technology Qingdao 266042 P. R. China
2. Institute of ChemistryChinese Academy of Sciences Beijing 100190 P. R. China
3. Department of Applied Biology and Chemical TechnologyThe Hong Kong Polytechnic University, Hung Hom, Kowloon Hong Kong SAR 999077 P. R. China
4. University of Chinese Academy of Sciences Beijing 100049 P. R. China