1. Division of Chemistry and Biological Chemistry; School of Physical and Mathematical Sciences; Nanyang Technological University; 21 Nanyang Link Singapore 637371 Singapore
2. Department of Chemistry and The State Key Laboratory of Molecular Engineering of Polymers; Fudan University; 220 Handan Road Shanghai 200433 P. R. China
3. School of Materials Science and Engineering; Nanyang Technological University; 50 Nanyang Avenue Singapore 639798 Singapore