氢键和π键对Gemini表面活性剂自组装行为的调控机制

Molecular self-assembly is the process of formation of aggregates with ordered structures,which is formed by intermolecular weak interactions spontaneously.The basic problem in self assembly system is to reveal the intrinsic link of intermolecular weak interaction,then controling the process of self-assembly, and preparing the self-assembly system with specific function.This project uses cationic Gemini surfactant with varied Molecular self-assembly is the process forming aggregates with ordered structures by weak intermolecular interactions spontaneously. The basic issues of investigation in molecular self-assembly system is to reveal the intrinsic link between weak intermolecular interaction, and regulate the process of self-assembly. This project focuses on cationic Gemini surfactant with varied structures and peculiar self-assembly behavior based on both ionic liquid crystal and interface crystal. The project investigates the regulating role of Gemini surfactant at different conditions by weak interactions. Examines the relationship between the weak interactions, such as hydrogen bond, π-π interaction, hytrophobic interaction and electrostastic attraction; analyzes the differences and relationship of self-assembly systems at different state; introduces both hydrogen bond and π-π interaction in Gemini surfactant to enhances intermolecular interaction, studies the contribution of hydrogen bond and π-π interaction on self-assembly system; analyzes the space matching relation and synergism between hydrogen bond and π-π interaction by means of the combination of the experimental results with MD simulation; and elabrates the ralationship between molecular structure and the property of self assembly system. The completion of the project has important theoretical value on promoting the application of new Gemini surfactant in major field, such as crude oil extraction, daily chemicals, etc.

分子自组装是分子通过分子间弱相互作用自发地形成具有有序结构聚集体的过程。分子自组装研究的基本问题是揭示分子间弱相互作用之间的内在联系，在此基础上实现对自组装过程的调控。本项目以具有丰富多样结构和奇特自组装行为的Gemini表面活性剂分子为研究对象，从离子液晶和界面结晶两方面入手，研究多种弱相互作用对Gemini表面活性剂在不同状态下自组装行为的调控作用。考察氢键、π-π堆积、疏水及静电等弱相互作用之间的关系；揭示Gemini表活性剂在不同状态下自组装行为的区别与联系；重点在Gemini表面活性剂分子中同时引入可提供氢键和π-π作用的基团，增加分子间的弱相互作用；研究氢键和π-π作用对自组装体系的贡献，采用实验与MD模拟相结合的方法分析氢键与π-π作用的空间匹配关系及协同作用；阐明分子结构与自组装体性能的关系。该项目的完成对推动Gemini表面活性剂在原油开采、日化领域的应用有重要的理论价值。

分子自组装是分子通过分子间弱相互作用自发地形成具有有序结构聚集体的过程。本项目主要以具有丰富多样结构和奇特自组装行为的Gemini表面活性剂分子为研究对象，研究多种弱相互作用对Gemini表面活性剂在不同状态下自组装行为的调控作用。在水溶液中，带相反电荷的有机盐的加入可在很大程度上促进Gemini表面活性剂胶束的生成和成长，同时有机盐同分异构体的机构对胶束的生成和成长具有显著的影响，这主要是由氢键、π键、静电作用、范德华力等多种相互作用的协同作用导致的。采用光响应将偶氮苯基团设计出拟四聚表面活性剂，研究了其在不同浓度下溶液的表面张力、粘弹性以及紫外光照前后体系的核磁共振与紫外吸收峰位移变化情况。该拟四聚表面活性剂在溶液中也可以形成高粘弹性的蠕虫状胶束。然而，该拟四聚表面活性剂粘弹体系对紫外光照没有刺激响应性。这主要是因为拟四聚体中分子之间的结合是通过正负电荷的吸引作用，是一种动态的平衡，光响应分子即使发生了顺反异构的变化，但由于偶氮苯基团的转化率较低，因此聚集体中会及时补充未转化的偶氮苯结构分子，导致聚集体结构不变，进而导致体系的宏观粘度不变。采用耗散粒子动力学(DPD)方法预测了Gemini表面活性剂在水溶液中的聚集形态。该类型Gemini表面活性剂随着浓度的增加，胶束形态从球状胶束、棒状胶束、层状胶束、反胶束网络结构逐渐转变，且连接基团长度的改变几乎不影响其在水溶液中的胶束形态转变。同时，Gemini表面活性剂的连接基团也对自组装体系的结构起到了非常关键的作用，Gemini 表面活性剂可以将球状聚集体连接成串珠结构，而传统表面活性剂却不能。此外，本项目还研究了β-环糊精聚合物（缩写为HDI-1）与不同分子结构的小分子（对硝基苯酚(PNP)，2,4,6-三硝基苯酚(TNP)，荧光素(Flu)，酚酞(Phth)）的相互作用机理。与β-环糊精单体相比，聚合物与有机物主要以两种作用相互结合，第一种作用表现为环糊精的包合作用，第二种作用表现为非包合作用。同时，氢键和π键对复合体系的相互作用起到了至关重要的作用。该项目的开展对推动Gemini表面活性剂在原油开采、日化领域的应用有重要的理论价值。基于本项目的研究成果，共发表论文10篇（其中SCI论文6篇），申请发明专利3项，培养研究生2人。