| 摘要註: |
本研究以自由基聚合反應將氮-異丙基丙烯醯胺(N-isopropylamide, NIPAAm)接枝到幾丁聚醣(Chitosan, CS)上,調查PNIPAAm、1CS-g-16PNIPAAm、1CS-g-10PNIPAAm等三樣品對溫度及pH之應答行為。實驗中以紫外光-可見光光譜儀(UV-Vis)、示差掃描熱卡分析儀(DSC)、及數位拍照等方法,調查水溶液樣品之較低臨界溶解溫度(LCST)隨接枝量之變化。以高壓DSC調查CO2壓力對LCST之影響,以接觸角測定儀量測不同pH值水溶液及不同成膜溫度之薄膜之親疏水性質隨接枝量之變化。實驗結果發現,水溶液樣品的LCST會隨pH值下降而下降,當以高壓DSC量測聚合物水溶液之LCST時,發現CO2壓力越高LCST越低,幾丁聚醣含量較少之樣品接觸角較低。成膜溫度40℃之薄膜樣品,有較高的接觸角(水滴在薄膜20秒後量測),可能因40℃為高於但較接近PNIPAAm之LCST的溫度,使得在40℃時PNIPAAm分子間較為緊縮,親水基團被包覆在PNIPAAm分子內,不易露出在薄膜外層,使得較為疏水。聚合物薄膜樣品在超臨界二氧化碳流體處理後,接觸角都會大幅的提高,使薄膜較不親水。處理壓力越高,薄膜的水接觸角會越高,處理時間越久,水接觸角也會越高。PNIPAAm薄膜在超臨界二氧化碳流體處理後,再以FTIR觀察,可得知因PNIPAAm與二氧化碳有交互作用,超臨界二氧化碳流體有乾燥PNIPAAm薄膜的效能。 In this study, chitosan (CS) was grafted with poly(N-isopropylacrylamide) (PNIPAAm) by free-radical polymerization. Three samples including PNIPAAm, 1CS-g-10PNIPAAm, and 1CS-g-16PNIPAAm were investigated on their temperature and pH responsive behavior. Ultraviolet/visible spectroscopy, differential scanning calorimetry (DSC), and digital photography were used to investigate the lower critical solution temperatures (LCST) of samples as a function of grafting amount. Effect of CO2 pressure on LCST, measured by a high pressure DSC (HP DSC), and pH value and temperature of aqueous solution on hydrophilic property of the film formed, determined by contact angle measurement, were investigated as a function of grafting amount. Experimental data found that LCST of sample decreased with decreasing pH value but with increasing CO2 pressure. The sample with lower CS content gave lower contact angle. The film formed at 40℃ gave relative high contact angle as measured 20 s after water was dropped on the film as compared to 20 and 60℃. The contact angle of film could be significantly enhanced after treatment by supercritical carbon dioxide fluid (scCO2), an indication that the film became less hydrophilic after scCO2 treatment. Higher pressure and longer time of CO2 treatment could both enhance contact angle of the film. The film could be effectively dried by the scCO2 treatment as analyzed by FTIR. |