1. Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, P. R. China
2. College of Science, Henan Agricultural University, Zhengzhou, Henan 450002, P. R. China
3. School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, P. R. China