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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/4144


    Title: 以脂肪酸鈉鹽界劑製備水凝膠之行為研究探討;Thermoreversible hydrogel formed by alkyl carboxylate salt in aqueous solution
    Authors: 林佳吟;Jia-yin Lin
    Contributors: 化學工程與材料工程研究所
    Keywords: 陰離子型界面活性劑;流變學;凝膠;Krafft 溫度;Rheology;Anionic surfactant;Krafft temperature;Hydrogel
    Date: 2009-05-25
    Issue Date: 2009-09-21 12:32:18 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 由於生醫材料以及組織工程在近期的快速發展,對於增加產品的生物降解性、生物相容性或是毒性等方面上,總是錙銖必較。不同以往高分子型凝膠對於環境的危害,利用界面活性劑獨特自我組裝的性質而形成的凝膠則是在近年來被廣泛的探討,原因在於利用非共價力而聚集的界劑分子相較於高分子在人體中更容易被自然排出,所以在許多材料的選擇往往被列為最優先的考慮,例如:創傷敷料。目前對於界劑型凝膠的研究多為陽離子型界劑系統為主,例如十六烷基三甲基銨溴化物。一般相信陽離子型界劑在加入芳香族鹽類後易形成如蟲狀般的微胞且彼此糾結、纏繞,而形成短暫的網狀結構,因此使系統顯現出具有黏彈的行為。 然而對於鮮少被討論的陰離子系統,則為本論文研究的目標,本文以傳統中製成肥皂的原料─脂肪酸鈉鹽界劑為對象,發現在低溫下於水相系統中能形成乳白色不透光的固體物,經由流變性質的量測證實了此物質確實為凝膠,並觀察出此凝膠為熱可逆型,透過差式掃描熱卡計等實驗法來定義出其溶膠─凝膠相轉變溫度。並更進一步地,探討在不同烷鏈長度或是不同濃度的脂肪酸型界劑,與其相轉變溫度之間的差異,並以傳統公認為熱可逆型凝膠的明膠作為各性物性的比較對象。藉由添加鹽類離子以及改變溶液的酸鹼值來比較對於界劑凝膠形成的影響程度,發現系統中存在的反離子種類會決定所形成凝膠的強度,鈉離子扮演著提升凝膠強度的角色,而其他等價離子(如鉀、鋰離子…等)則是扮演著降低強度的角色。最後透過電子顯微鏡來分析此界劑凝膠的表面微結構。 A physical gel is a substantially dilute network in which junctions can break and recombine due to thermal fluctuation, i.e., the junctions have the finite lifetime. When in the steady-state, it exhibits no flow. In general, reversible gels are formed by polymers, with weak attractions like hydrogen bonds, for example, biopolymers gelatin and agar. Typically, the surfactant gel is referred to the cationic surfactant/water system involving cetyl-trimethylammonium bromide (CTAB). However, it is generally believed that CTAB surfactant molecules assemble into worm-like micelles in aqueous media and yield a transient network structure due to the topological entanglement of the micelles. As a result, it is more like a viscoelastic solution rather than a jelly-like gel. In this work, the gelation of a surfactant solution involving anionic surfactant/water system including sodium laurate (NaL) and sodium tetradecanoate (NaM) is explored by rheological properties measurement and differential scanning calorimetry. The surfactant solution transforms from a transparent liquid to a white opaque gel upon lowering the temperature and vice versa. The characteristics of the surfactant gel is confirmed by the fact that the storage module G”is greater than the loss module G”. In addition to investigate the gelling mechanism such as the nature of associative bonds and microscopic structure, the effects of surfactant concentration, alkyl chain length, and salt addition on the gel properties are studied as well.
    Appears in Collections:[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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