1. Department of Polymer Science and Engineering, School of Chemistry and Biological Engineering; University of Science and Technology Beijing; Beijing 100083 P. R. China
2. State Key Laboratory of Chemical Resource Engineering; Beijing University of Chemical Technology; Beijing 100029 P. R. China
3. State Key Laboratory of Power Transmission, Equipment and System Security; Chongqing University; Chongqing 400030 P. R. China