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

在这个由美国国家科学基金会化学部大分子、超分子和纳米化学项目资助的项目中，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是如何在水中自组装的。在小分子表面活性剂中，一个水溶性的头基团附着在一个不溶于水的尾基团上。在高表面活性剂浓度的水中，这些分子自发地形成各种结构上周期性的软材料，称为液晶。某些液晶结构在实际技术应用中特别有用，但这些结构难以接近且其性能有限。该项目通过研究如何在水/表面活性剂混合物中添加盐和油来形成这些有用的液晶来解决这些问题。所得材料的一个子集可能在治疗性药物输送等领域找到长期应用。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，用于高效分离复杂的化学混合物，以及产生和使用来自太阳能的可再生燃料。这项工作的更广泛的影响包括指导研究生和本科生在基础科学和技术创新之间的研究项目，这将有望为未来的医疗保健和可再生能源应用带来有用的材料。本项目研究了小分子添加剂如何控制双子星（“双尾”）二羧酸表面活性剂的水浓度依赖性自组装，以形成溶性液晶（LLCs）。在这个项目中，特别强调的是确定稳定网络相llc的方法，这些网络相llc具有相互交织的、周期性的和渗透的水性和疏水性3d网络。通过偏振光显微镜和温度相关x射线散射，评估了各种亲水、疏水和两亲性分子添加剂对LLC结构形成和稳定性的影响。这些研究为活性表面活性剂和分子添加剂的混合物的开发提供了信息，这些混合物可以自发形成网络相llc，用于随后的聚合，形成功能性的纳米多孔聚合物膜。Mahanthappa教授正在将相关研究成果转化为公共推广演示，展示简单的“肥皂”在石油和天然气开采的水力压裂应用（“水力压裂”）中的效用，让公众参与到更广泛的能源收集技术和全球能源需求的讨论中来。

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.