1. Research Institution for Biomimetics and Soft Matter College of Physical Science and Engineering; Fujian Key Provincial Laboratory for Soft Functional Materials Research; Xiamen University; 422 Siming Nan Road Xiamen 361005 P. R. China
2. Key Laboratory of Textile Science and Technology; Ministry of Education, College of Textiles; Donghua University; 2999 Renmin Bei Road Shanghai 201620 P. R. China
3. Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
4. College of Electron Information and Engineering; Hebei University; Baoding 071002 P. R. China