| 초록 |
Temperature sensitive polymers are the most intensively investigated by a simple design principle that hydrophilicity and hydrophobicity balance. The transition temperature whether LCST or sol-to-gel transition temperature decreases, as the hydrophobicity of a polymer increases. Here, we are reporting monomethoxy poly(ethylene glycol)-DL-polyalanine (mPEG-DL-PA) as an opposite case of above hydrophilicity/hydrophobicity rule in predicting transition temperature. A series of mPEG-DL-PAs were synthesized by ring-opening polymerization. All polymers formed an transparent aqueous solution in a concentration range of 5~20 wt. % and the aqueous solutions underwent sol-to-gel transition as the temperature increased. To understand the unique transition behaviour, 500-620, 500-1160, and 500-2820 were selected and their phase behaviour and solution properties were intensively investigated using FTIR, circular dichroism, NMR, cryo-TEM. |
