1. Polymer Research Group; Faculty of Science; Department of Chemistry; Chiang Mai University; Chiang Mai 50200 Thailand
2. Materials Science Research Center; Faculty of Science; Chiang Mai University; Chiang Mai 50200 Thailand
3. Aston Institute of Materials Research; Aston University; Birmingham B4 7ET UK
4. Chemical Engineering and Applied Chemistry; School of Engineering and Applied Science; Aston University; Birmingham B4 7ET UK