1. School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P. R. China
2. State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, P. R. China
3. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
4. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada