四氯化碳-水-十六烷基三甲基溴化铵三元体系凝胶的生成机理初探

Preliminary Investigation on the Formation Mechanism of CCl_4-Water-Cetyl Trimethyl Ammonium Bromide (CTAB) Gel

自从1921年凝胶首次由小分子制得以来,小分子凝胶研究已经有了一定的进展。特别是近几十年小分子凝胶在医药、化妆品、食品、卫生用品等各个领域应用,被人们广泛关注。但到目前为止,人们对基于表面活性剂的小分子凝胶的结构和生成机理,特别是水、有机溶剂和表面活性剂在形成小分子凝胶过程中的作用仍认识十分有限。可使用水、四氯化碳和三甲基十六烷基溴化铵(CTAB)制出了一种小分子凝胶,并根据滴定和XRD实验结果提出了水和四氯化碳协同增溶表面活性剂CTAB形成凝胶的机理。红外光谱与核磁共振实验结果证明CTAB在凝胶中通过分子堆砌形成准有序结构。

Gels are gaining extensive interest owing to their versatile applications in fields such as drug delivery,tissue engineering,cosmetics,templated materials and food industry.Surfactants have an ability to self-assemble into a variety of supramolecular aggregate structures and morphologies.Of particular interest in resent years are surfactant-based gels,one special class of materials due to surfactant assemblies resulting in viscoelastic solid-like rheological behaviors.Up to now,there is only limited understanding on the mechanism of gel formation,especially on the interaction among water,organic solvents and surfactant during thegel formation.In this study we prepare a Low-molecule-gel that is composed of cetyl trimethyl ammonium bromide（CTAB）,water and carbon tetrachloride.Based on the experimental result of XRD and titration,the authors find that CTAB in gel are more than in saturated CTAB solution but CTAB is not solide in gel.CTAB is not solvented in CCl4.The solubility of CTAB in saturated CTAB solution is limited.So the authors suppose that CTAB is a synergistically solubilized by water and CCl4 in the gel.In addition,both NMR and FTIR spectroscopic results demonstrate that CTAB cations form a quasi-ordered structure in the gel.