1. Xiamen University; Research Institute for Soft Matter and Biomimetics, Department of Physics, Fujian Provincial Key Laboratory for Soft Functional Materials Research; 422 Siming S Rd, Siming Qu Xiamen 361005 China
2. Georgia Institute of Technology; School of Materials Science and Engineering; 771 Ferst Drive, NW Atlanta GA 30332-0245 USA
3. National University of Singapore; Faculty of Science, Department of Physics; 21 Lower Kent Ridge Road Singapore 119077 Singapore