1. Interdisciplinary Graduate School; Nanyang Technological University; Singapore 639798 Singapore
2. Singapore Membrane Technology Center; Nanyang Environment and Water Research Institute; Nanyang Technological University; Singapore 637141 Singapore
3. School of Chemical and Biomedical Engineering; Nanyang Technological University; Singapore 637459 Singapore
4. Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education; School of Chemistry and Chemical Engineering; Sun Yat-sen University; Guangzhou 510275 P. R. China