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  • 學位論文

新穎界面活性劑的合成和聚集行為

The Synthesis and Aggregate Behaviors of A Novel Surfactant

指導教授 : 牟中原
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摘要


界面活性劑特有的親水和親油性質及其在不同相中自組裝的聚集行為,是近十年來備感興趣的研究之一。此乃因界面活性劑多變的聚集形態不僅可用以當作各種多孔材料的製備模板,也可用於藥物輸送等生醫上的應用。因此,合成新型具更多功能,且能調控其聚集型態的界面活性劑是一大挑戰。此論文的研究方向分為兩個部份。第一部份是合成對pH靈敏的二羧酸兩性分子(dicarboxylate surfactant),並研究二羧酸兩性分子在不同的pH值下在水溶液中的聚集行為。在高pH環境下,二羧酸兩性分子的兩個酸基上的氫原子將會被完全地拔掉,這將會導致二羧酸兩性分子間的靜電排斥力加大以及堆積參數變小,進而產生一高曲率的微胞聚集物。當pH值逐漸降低時,二羧酸兩性分子的兩個酸基將會逐漸地被質子化,這將會使二羧酸兩性分子間的靜電排斥力變小以及堆積參數變大,進而產生一較低曲率的囊胞聚集物,甚至是酸皂的沉澱。 第二部份是探討一陽離子螢光界面活性劑在水溶液中的聚集行為。由於陽離子螢光界面活性劑具螢光基團,因此其在水溶液中的聚集行為會影響其螢光的放射波長與強度。當陽離子螢光界面活性劑的濃度超過臨界微胞濃度時,將促使激發雙子的形成,導致螢光界面活性劑的螢光波長紅位移。另外將溶劑從較高極性的水換成較低極性的甲醇和乙醇,會導致聚集物崩解成界面活性劑單體,進而促使螢光波長藍位,而且由於減低了水的影響,將增加陽離子界面活性劑發光的量子效率,此稱之為”溶劑致發光”效應。最後我們討論了混合離子界面活性劑的在水溶液中聚集行為。我們添加不同比例的陰離子界面活性劑十二烷基磺酸鈉(SDS)到陽離子界面活性劑溶液中,發現陰離子界面活性劑會藉由靜電吸引力插入陽離子界面活性劑的聚集中,進而促使螢光波長逐漸地藍位移,而且由於陰離子界面活性劑隔開了陽離子界面活性劑,減低了陽離子界面活性劑自身驟熄的影響,增加了陽離子界面活性劑發光的量子效率,此稱之為”活性劑致發光”效應。

關鍵字

界面活性劑 pH靈敏 聚集 微胞 囊胞 螢光

並列摘要


The pH-sensitive anionic surfactant has been synthesized and its aggregate behaviors in the aqueous solution have been studied at different pH value. At higher pH value, the anionic surfactant will be fully de-protonated as a divalent molecule and generate higher curve aggregate, micelle. At lower pH value, the anionic surfactant will gradually be protonated and generate lower curve aggregate, vesicle or acid soap precipitate. The driving force that dominates their packing behaviors is hydrogen bonding generated from adjacent partial protonated surfactants. The cationic fluorescent surfactant has been synthesized and its aggregate behaviors in the aqueous solution have been studied by fluorescence measurements owing to its intrinsic fluorescent probe. When surfactant concentrations increase above the critical micelle concentration (CMC), the emission wavelength would red shift because of excimer formation. Furthermore, the emission wavelength will not only shift to shorter wavelength but also increase quantum efficiency in less polar medium owing to the de-formation of aggregate. Similarly, the addition of anionic surfactant sodium dodecyl sulfate into the surfactant solution at different ratio also gives rise to the blue-shift wavelength and the increase of quantum efficiency.

參考文獻


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