【作者】 蔡波；

【导师】 董金凤；

【作者基本信息】 武汉大学 ， 应用化学， 2012， 博士

【摘要】 Gemini表面活性剂,作为一种新型的表面活性剂,在最近几十年得到了广泛的关注。因其结构上的特殊性,Gemini表面活性剂较传统表面活性剂具有更好的性质：如较高的表面活性,较低的临界胶束浓度,丰富的聚集行为以及较低的Krafft点。由于表面活性剂在科学研究和实际应用上的广泛应用,合成一些新的具有特殊结构的Gemini表面活性剂已经成为化学,生物,材料领域的研究的热点话题。本文通过对分子结构进行调控,合成了两大类以五元杂环为头基的Gemini表面活性剂：以吡咯烷为头基的阳离子型Gemini表面活性剂和以酰亚胺为头基的pH敏感型的Gemini表面活性剂。通过表面张力,电导率,荧光探针,动态光散射,冷冻透射电镜,扩张流变技术对它们的溶液和界面性质进行了系统的研究。本论文主要分为以下六个部分：(1)论文的第一部分概述了Gemini表面活性剂的发展,合成,特性以及应用。发现了合成新型Gemini表面活性剂的必要,为本论文的开展提供了理论依据。(2)论文的第二部分合成了两大系列的以五元杂环为头基的Gemini表面活性剂：以吡咯烷为头基的阳离子型Gemini表面活性剂和以酰亚胺为头基的pH敏感型的Gemini表面活性剂。并且通过核磁共振(NMR),高分辨率质谱(ESI-MS),偏光显微镜(POM)和元素分析(EA)等方法对它们的结果进行了表征。结果表明,合成的产物均为目标产物且具有非常高的纯度。(3)论文的第三部分采用表面张力,电导率,荧光探针等方法考察了不同疏水尾链长度的吡咯烷型Gemini表面活性剂Cn-4-nPB(n=10,12,14,16)的表面活性和胶束化性质。通过对Cn-4-nPB和m-s-m型(CsH2s+1-α,ω-(CmH2m+1N+(CH3)2)2)Gemini表面活性剂比较,发现以杂环为头基的Gemini表面活性剂Cn-4-nPB具有更高的表面活性。同时发现改变疏水尾链对Gemini表面活性剂的胶束化也有着比较大的影响：当疏水尾链为n=10,12,14时,胶束化过程以熵驱动作为主导驱动；当连接疏水尾链增加到16时,胶束化过程则以焓驱作为主导驱动。(4)论文的第四部分采用表面张力,电导率,荧光探针,动态光散射,冷冻透射电镜等方法考察了不同连接基团长度的吡咯烷型Gemini表面活性剂C12-s-12PB(s=3,4,6,8,10,12,14,16)的表面活性和胶束化性质。通过比较,发现其与m-s-m型Gemini表面活性剂变化规律不同的地方：极限吸附面积随着连接基团长度增加而增加。并基于Gibbs吸附公式运用局限性,对此进行了详细的阐述。通过表面张力、电导率、荧光探针、紫外可见分光光度、动态光散射和冷冻透射电镜的测试方法从多方面论证了C12-14-12PB和C12-16-12PB溶液中预胶束和双拐点现象。通过电导率研究通过获得热力学参数的分析,发现疏水尾链和连接基团中CH2基团在胶束化时的贡献是不同的。(5)论文的第五部分采用π-A等温线和扩张液滴技术对C18-s-18PB (s=3,8,12)表面活性剂的界面单分子膜及其粘弹性进行了研究。π-A等温线的研究结果表明,不同连接基团长度的C18-s-18PB的单分子膜都处在液态扩张膜。扩张液滴技术的研究结果表明,表面活性剂的连接基长度,外界扰动频率和表面压均对界面膜的扩张粘弹性有着重大的影响。(6)论文的第六部分采用pH滴定,表面张力,荧光探针等方法研究了疏水尾链和pH对酰亚胺为头基的Gemini表面活性剂Di-CnPO的表面活性和胶束化性质的影响,进而研究了pH诱导溶液聚集体结构的转变。更多还原

【Abstract】 Gemini surfactants, which are the new type of surfactant, have attracted much attention in recent years. Due to their special molecular structures, Gemini surfactants are often superior to the corresponding single tailed partners in various properties, such as higher surface activity, lower critical micelle concentration, rich aggregation behavior, lower Krafft points etc. Because surfactants are widely used in scientific research and practical application, synthesis of some new Gemini surfactants with special structure has become a hot research topic in the field of chemistry, biological and materials. For the regulation the structure in molecular, two types of Gemini surfactants with five-membered heterocyclic headgroups have been synthesized:one is the cationic Gemini surfactants with pyrrolidinium headgroups, the other one is the pH sensitive Gemini surfactants with imide headgroups. The aqueous solution and monolayer were studied by employing various techniques, such as surface tension, fluorescence, conductivity, dynamic light scattering, cryo-transmission electron microscopy (cryo-TEM), and dilatational rheological. This thesis is organised into six parts.In the first section, the history, synthesis, the special properties and application of Gemini surfactants are summarized. It was be found that the synthesis of novel Gemini surfactant is necessary, which provided a basis to carry out this thesis.In the second section, two types of Gemini surfactants with five-membered heterocyclic headgroups have been synthesized:one is the cationic Gemini surfactants with pyrrolidinium headgroups, the other one is the pH sensitive Gemini surfactants with imide headgroups. All the products were characterized by the methods of NMR, ESI-MS, POM and EA. The results show that all the products are object and have highly purity.In the third section, we investigated the surface activity and micellization of Gemini surfactants Cn-4-nPB (n=10,12,14,16) in aqueous solutions by employing various techniques such as surface tension, fluorescence, and conductivity. It can be found that Gemini surfactants Cn-4-nPB with heterocyclic head group had higher surface activity when compared with the m-s-m (CsH2s+1-α,ω-(CmH2m+1N+(CH3)2)2) type Gemini surfactants. It also can be found that the hydrophobic tails had significant effects on the micellization:the micellization is mainly entropy driven in the surfactant with shorter hydrophobic chain length (n＝10,12,14) but enthalpy driven in the surfactant with longer hydrophobic chain length (n=16).In the fourth section, we used surface tension, fluorescence and conductivity and studied the surface activity and micelliaztion of the Gemini surfactants C12-S-12PB with different spacer chain length (s=3,4,6,8,10,12,14,16). It can be found that the properties of C12-S-12PB are different with m-s-m Gemini surfactants:the minimum average areas per surfactant molecule for C12-S-12PB are increased with increasing spacer chain length. It can be explained by the limitations of the Gibbs adsorption formula. Through the surface tension, conductivity, fluorescent probe, UV visible spectrophotometer, dynamic light scattering and cryo-transmission electron microscopy measurements, it was found that the premicelle formation and double breakpoints exists in the solutions of C12-14-12PB and C12-16-12PB. It can be seen in the conductivity measurement that there is a significant difference of the effect of methylene groups in the hydrophobic tail and the spacer on the micellizationis.In the fifth section, we used π-A isotherms and expansion droplets to study the properties of monolayer and dilatational viscoelasticity of the C18-S-18PB (s=3,8,12). From the π-A isotherms, it can be found that all the monolayers of the surfactants used here are liquid core expanded film. The expansion droplet technology results show that the spacer length, disturbance frequency and surface pressure all affected dilatational viscoelasticity of the interfacial film.In the sixth section, we used pH titration, surface tension and fluorescent measurement to study the effects of the pH and hydrophobic tails on the surface activity and micellazation for the Gemini surfactants with imide headgroups. It was found that the aggregation transition in the aqueous solution was induced by pH.更多还原