1. College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, Sichuan, P. R. China
2. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, United States
3. Department of Polymer Science, University of Akron, Akron, Ohio 44325-3909, United States