1. Department of Chemistry, Faculty of Science; Mahidol University; Rama VI Rd Rajdhevee Bangkok 10400 Thailand
2. MTEC, National Science and Technology Development Agency; 114 Thailand Science Park, Paholyothin Rd, Klong 1 Klong-Luang Pathumthani 12120 Thailand
3. Rubber Technology Research Centre (RTEC), Faculty of Science, Mahidol University; Phutthamonthon 4 Rd Salaya Nakornprathom 73170 Thailand