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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71333

    Title: 分子構型與表面電荷密度對雙子型陰陽離子界面活性劑系統之相行為影響;Self-assembling Behavior of Gemini Catanionic Surfactant Systems: Effect of Molecular Configuration and Surface Charge Density
    Authors: 蘇慧明;Su,Hui-Ming
    Contributors: 化學工程與材料工程學系
    Keywords: 雙子型界面活性劑;陰陽離子系統;相行為;表面電荷密度;gemini surfactant;catanionic system;phase behavior;surface charge density
    Date: 2016-08-03
    Issue Date: 2016-10-13 12:44:42 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 陰陽離子界面活性劑系統是由陽離子與陰離子界面活性劑所混合組成。隨著表面電荷密度(意即陰、陽離子界面活性劑之混合比例)與含水量的變化,此系統可表現出豐富的自組裝行為,包括自發形成生技醫藥應用上的重要結構—單層囊泡,使得陰陽離子界面活性劑系統受到許多的關注。長期以來,關於「陰陽離子界面活性劑系統」的研究皆是以「單鏈型」陽離子和陰離子界面活性劑所組成之系統為主,而以「雙子型」陽離子和陰離子界面活性劑所組成的系統則罕見於相關研究之中。雙子型界面活性劑是由兩個單鏈型界面活性劑以分子鏈連接所構成之界面活性劑;因橋接分子鏈的存在而額外提供的構型自由度,往往使得此類型的界面活性劑擁有更為豐富的相行為。有鑑於相關研究的缺乏,本研究之研究目的即在於探討以雙子型界面活性劑為基礎之陰陽離子界面活性劑系統的自組裝行為和物理性質。我們利用對外觀的檢驗、偏光顯微鏡、動態光散射和小角X光散射以及流變儀等技術,研究雙子型陰陽離子界面活性劑系統的特性以及改變表面電荷密度與橋接分子鏈接長度對其相行為及流變性質上的影響。我們發現,雙子型陰陽離子界面活性劑系統可於眾多組成成分下自發形成單層囊泡;而其自組裝結構的相變化行為,則與表面電荷密度高度相關。當表面電荷密度越大時,分子間的電荷斥力越大,分子越傾向於形成高曲率之結構(如:微胞或膠束);反之,當表面電荷密度越低時,分子間的電荷斥力越弱,分子越傾向形成低曲率之結構(如:多層狀雙層膜結構),並會因陰、陽離子解離程度上的不同而產生相分離的現象。然而,橋接分子鏈的長度雖會對相行為產生影響,但並無顯著之規則可循。;A catanionic surfactant system is an aqueous mixture of cationic and anionic surfactants. This type of systems display rich self-assembling behavior when the surface charge density (i.e., the molar ratio of the constituent surfactants) and water content are varied, with the spontaneous formation of the pharmaceutically important structure, unilamellar vesicle, being a particularly encouraging observation for the systems. While considerable efforts have been dedicated to the catanionic systems constituted by conventional surfactants, researches on the systems composed of cationic and anionic gemini surfactants are rare, if any. Gemini surfactants are a family of novel surfactants which distinguished themselves from conventional surfactants with their spacer-linked dimeric molecular configuration; the additional degrees of freedom afforded by the presence of the spacer often make the phase behavior of the gemini surfactants even richer. Given the lack of the relevant researches, this present study aspires to investigate the physicochemical properties and self-assembling behavior of the unexplored gemini catanionic systems. We exploit visual inspection, polarized microscopy, dynamic light scattering, small angle X-ray scattering and rheology to study the influences of the surface charge density and spacer length on the phase behavior and rheological properties of a gemini catanionic system. It is found that the vesicles were spontaneously formed in a wide composition range for the gemini catanionic systems; and the phase behavior of the systems is highly dependent on the surface charge density. The larger the surface charge density is, the stronger the intermolecular repulsions and the higher the tendency of forming highly curved structures (e.g., micelles)are; on the contrary, approaching to electric neutrality for the surface results in weakened electrostatic repulsions between molecules and in enhanced propensity of forming structures with low surface curvatures (e.g., lamellar structures), which is accompanied by the occurrence of phase separation arising from the discrepancy in the ionization of the gemini surfactants. Nevertheless, the mechanism of how the spacer length affects the phase behavior of the catanionic systems is not clear even though this influence is indeed present.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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