Xiaofei Zhao1,2, Baohua Zhang1, Ruyan Zhao1,2, Bing Yao1,2, Xuejing Liu1,2, Jun Liu1, Zhiyuan Xie1
1State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
2University of Chinese Academy of Sciences, Beijing 100049, P.R. China