1. School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, P.R. China
2. National Engineering Research Center of Flame Retardant Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, P.R. China
3. College of Advanced Interdisciplinary Science and Technology, Henan University of Technology, Zhengzhou 450001, P.R. China
4. Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 Singapore