1. College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, P. R. China
2. State Key Laboratory for Mechanical Behaviour of Materials, Shanxi International Research Center for Soft Matter, Xi’an Jiaotong University, Xi’an 710049, P. R. China
3. Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, 621999 Mianyang, P. R. China