1. College of Polymer Science and Polymer Engineering The University of Akron Akron OH 44325 USA
2. Beijing National Laboratory for Molecular Sciences Center for Soft Matter Science and Engineering the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
3. Tianjin Key Laboratory of Molecular Optoelectronic Sciences School of Science Collaborative Innovation Centre of Chemical Science and Engineering Tianjin University Tianjin 300072 P. R. China