1. School of Chemistry and Chemical EngineeringHunan University of Science and Technology Xiangtan Hunan 411201 P. R. China
2. Key Laboratory of Synthetic Chemistry of Natural SubstancesShanghai Institute of Organic ChemistryChinese Academy of Sciences Shanghai 200032 P. R. China
3. Hunan Provincial Key Laboratory of Controllable Preparation and Functional Application of Fine PolymersHunan University of Science and Technology Xiangtan Hunan 411201 P. R. China