Influence of Small Molecule Additives on Gemini Dicarboxylate Lyotropic Liquid Crystal Structure and Stability

在这个由NSF化学部大分子，超分子和纳米化学计划资助的项目中，威斯康星大学麦迪逊分校的Mahesh Mahanthappa正在研究小分子表面活性剂如何在水中自组装，其中水溶性头部基团连接到水不溶性尾部。在水中高浓度的表面活性剂下，这些分子自发地形成各种结构周期性的软材料，称为液晶。某些液晶结构在实际的技术应用中特别有用，然而这些结构难以获得并且它们的性质受到限制。该项目通过研究如何将盐和油添加到水/表面活性剂混合物中来解决这些问题，从而形成这些有用的液晶。所得材料的子集可以在诸如治疗药物递送的领域中找到长期应用。该项目的另一个方面侧重于将这些液晶转化为有用的聚合物膜，用于复杂化学混合物的节能分离以及太阳能可再生燃料的生产和使用。这项工作的更广泛影响包括指导研究生和本科生从事基础科学和技术创新之间的研究项目，本项目研究了小分子添加剂如何控制水浓度依赖的Gemini自组装，在一个实施方案中，所述方法包括将双尾（“双尾”）二羧酸盐表面活性剂转化为溶致液晶（LLC）以形成溶致液晶。该项目的一个特别重点是确定稳定网络相LLC的方法，该网络相LLC具有交织的，周期性的和分散的水和疏水域的3D网络。各种亲水性，疏水性和两亲性分子添加剂的LLC结构的形成和稳定性的影响正在评估通过偏振光显微镜和温度依赖性X射线散射。这些研究为反应性表面活性剂和分子添加剂的混合物的开发提供了信息，这些混合物自发地形成网络相LLC，用于随后聚合成功能性纳米多孔聚合物膜。Mahanthappa教授正在将相关的研究成果转化为公众宣传演示，展示简单的“肥皂”在水力压裂应用（“水力压裂”）中的效用，用于石油和天然气回收，让公众参与更广泛的能量收集技术和全球能源需求的讨论。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Mahesh Mahanthappa of the University of Wisconsin-Madison is studying how small molecule surfactants, in which a water-soluble headgroup is attached to a water-insoluble tail, self-assemble in water. At high surfactant concentrations in water, these molecules spontaneously form a variety of structurally periodic soft materials known as liquid crystals. Certain liquid crystal structures are particularly useful in practical technical applications, yet these structures are difficult to access and their properties are limited. This project addresses these problems by investigating how adding salts and oils to water/surfactant mixtures enables the formation of these useful liquid crystals. A subset of the resulting materials may find long term application in fields such as therapeutic drug delivery. Another aspect of this project focuses on converting these liquid crystals into useful polymer membranes for energy efficient separations of complex chemical mixtures and for the generation and use of renewable fuels derived from solar energy. The broader impacts of this work include mentoring graduate and undergraduate students in research projects at the boundary between fundamental science and technological innovation, which will is expected to lead to useful materials for future healthcare and renewable energy applications.This project investigates how small molecule additives control the water concentration-dependent self-assembly of gemini ("twin tail") dicarboxylate surfactants to form lyotropic liquid crystals (LLCs). A special emphasis in this project is placed on identifying methods for stabilizing network phase LLCs with interwoven, periodic, and percolating 3D-networks of aqueous and hydrophobic domains. The influence of various hydrophilic, hydrophobic, and amphiphilic molecular additives on LLC structure formation and stability are being evaluated by polarized light microscopy and temperature-dependent X-ray scattering. These studies are informing the development of mixtures of reactive surfactants and molecular additives that spontaneously form network phase LLCs for subsequent polymerization into functional, nanoporous polymer membranes. Professor Mahanthappa is translating related research results into public outreach demonstrations that showcase the utility of simple "soaps" in hydraulic fracturing applications ("fracking") for oil and gas recovery, to engage the public in broader discussions of energy harvesting technologies and global energy demands.