1. College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, P. R. China
2. Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, Key Laboratory of Advanced Functional Polymeric Materials of College of Hunan Province, and Key Laboratory of Environment-Friendly Chemistry and Application in Ministry of Education, Xiangtan University, Xiangtan 411105, Hunan Province, P. R. China