【作者】 杜恣毅；

【导师】 游毅；

【作者基本信息】 福州大学 ， 有机化学， 2003， 硕士

【摘要】 探索并合成具有高表面活性的新型表面活性剂一直是人们感兴趣的课题。普通表面活性剂分子中含有一条亲油链和一个亲水基，而Gemini表面活性剂可看作是由两个单链单头基普通表面活性剂在离子头基处通过化学键联接而成的一种新型表面活性剂。实验表明，Gemini表面活性剂普遍具有比普通表面活性剂高得多的表面活性。不仅如此，通过变化Gemini表面活性剂的分子结构，还创造了从分子水平上调控分子间弱相互作用力的可能性，也可望由此产生丰富多样的分子有序聚集体形状与特性。目前关于此类化合物的研究已成为表面化学研究的热点领域。在这些研究中，设计合成合适的Gemini表面活性剂是一个关键。从合成思路上看，Gemini表面活性剂的合成通常有如下三种方式：①选择或设计合适的联结剂，先在联结剂上引入两条疏水链，最后再引入两个亲水基；②选择或设计合适的联结剂，先在联结剂上引入两个亲水基，最后再引入两条疏水链；③选择或设计合适的双亲体，再用一联结剂直接将两双亲体联接起来。在实际合成中，如果有合适的原料，还可对合成路线作进一步的简化，但不管采取哪种合成方式，合成中得到的中间体需要包含有可供进一步反应的活性部位，并且这个活性部位要在亲水基、疏水链、联接基团三者键合处附近。这一点是开始设计合成路线或者选择起始原料时所要考虑的关键环节。目前文献中所见到的羧酸盐Gemini表面活性剂的合成采用了第①、②种合成方式。本论文采用第③种合成方式，以长链羧酸为起始原料，利用Hell-Volhard-Zelinsky反应在羧酸的α位引入溴原子使之活化，然后再通过Williasom醚化反应，用联结剂（对苯二酚、乙二醇、1,4－丁二醇、乙二硫醇）将两长链羧酸联结起来，即可得到一系列新型羧酸盐Gemini表面活性剂。总的看来，本合成路线具有原料来源丰富，路线简捷等优点。在本论文中，共合成了六种新型羧酸盐Gemini表面活性剂，所有产品经元素分析、红外光谱、氢核磁共振谱等进行结构表征，它们的结构如下图所示：<WP=3>本论文还测定了这些表面活性剂的临界胶团浓度及反离子结合度，并在此基础上考察了胶团化过程的热力学性质(以质量作用定律为模型，估算了胶团化过程的焓变、熵变、吉布斯自由能变化)。与单烃链单亲水基羧酸盐表面活性剂相比，所合成的Gemini表面活性剂的cmc值小了约一个数量级，可见引入联接链后的Gemini表面活性剂生成胶团的能力相当强。从热力学角度看，本论文中所合成的Gemini表面活性剂的吉布斯自由能变化值比一般的表面活性剂小了许多, 这也显示了Gemini表面活性剂比单烃链单亲水基表面活性剂具有更强的胶团化能力；它们的－T(Som值均明显小于(Hmo值，表明它们在水溶液中的胶团化主要来自熵效应的驱动。进一步的分析表明，胶团化过程中还存在焓/熵补偿现象。更多还原

【Abstract】 New surfactant molecules are unremittingly appearing on account of the large research work aimed at increasing the performance of surfactant formulations. Comparing to ordinary surfactants which have single hydrophobic and single hydrophilic group per molecule, Gemini surfactants are made up of two amphiphilic moieties connected at the level of the head groups by a spacer group. Most research work have manifested that Gemini surfactants have higher performance than ordinary surfactants. It also makes prospective that we can control the delicate mutual forces at the level of molecule by changing the structure of Gemini surfactants, and as a result it will bring about interesting rheological properties. Owing to this, studies on the novel surfactants have attracted considerable attention in surface chemistry domain.To starting the research work, it is crucial to design and synthesize appropriate Gemini surfactants first. Generally, the methods used to synthesize Gemini surfactants are as follow: ①chose or design an appropriate coupling agent, then introduce two hydrophobic groups and two hydrophilic groups sequentially into the coupling agent; ②chose or design an appropriate coupling agent, then introduce two hydrophilic groups and two hydrophobic groups sequentially into the coupling agent; ③chose or design an appropriate amphiphilic molecule, then use a coupling agent to link the two amphiphilic molecules. In fact, selecting an appropriate material may simplify the synthesis route. But no matter what route you should chose, the intermediate must provide active parts for further reaction, and the active parts should be close to the joint of the hydrophobic group, the hydrophilic group and the spacer group. This is a key point when we consider designing the synthesis route or selecting the starting material.Until now, the synthesis of the carboxylate Gemini surfactants appearing on the literature only adopted method ① and ②. In this thesis, we adopt method ③: Start from<WP=5>long-chain fatty acids, use Hell-Volhard-Zelinsky α-Halogenation of fatty acid to prepare the intermediate (α-brominated fatty acids), then react the intermediate with the coupling agent (Benzene-1,4-diol; Ethane-1,2-diol; Butane-1,4-diol; Ethane-1,2-dithiol) via Williamson synthesis of ether, finally a series of carboxylate Gemini surfactants are obtained. In total, the synthesis route has the merits that the materials are in abundance and the route is shortcut.In this thesis, totally six kind of new carboxylate Gemini surfactants are synthesized. All products are characterized by elementary analysis, IR spectra and 1H-NMR spectra. Their structures are as follow:Also the critical micelle concentration and the counterion ionic association degree are determined. Based on mass action model, the Gibbs free energy, enthalpy and entropy changes in the process of micellization are evaluated. The values of cmc of the carboxylate Gemini surfactants are about one order of magnitude lower than the surfactant with single chain and single carboxylate group, showing that the Gemini surfactants are more efficient in forming micelle. It is also confirmed by the fact that the values of Gibbs free energy change of the Gemini surfactants are smaller than ordinary surfactants. On the other hand, the values of －T(Som are smaller than that of (Hmo , showing that the micellization is an entropy-driven process. Besides the enthalpy-entropy compensation phenomena are also investigated.更多还原