1. Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MOE), National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China
2. Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
3. Department of Physics and Soft Materials Research Center, University of Colorado Boulder, Boulder, Colorado 80309-0390, United States
4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States