RII Track-4: Use of Positron Annihilation Lifetime Spectroscopy to Engineer Membrane Selective Layers

该项目寻求建立在阿拉巴马大学塔斯卡卢萨分校(UA)水研究的基础上。阿拉巴马州拥有丰富的天然水源和通往墨西哥湾的通道，是研究水处理工艺的理想地点。因此，UA将水作为其四大研究支柱之一，为所有人提供更好的水质。聚酰胺膜，通常称为反渗透或反渗透膜，通常用于海水淡化。然而，它们的分子水平性质还没有被很好地理解。该项目将允许UA的研究人员在国家标准与技术研究所(NIST)进行研究，以学习一种新技术来表征水处理聚合物膜的分子级特性。这项研究试图从分子水平上了解合成条件如何影响膜的性能，特别是那些涉及海水淡化的条件。聚合物表征技术将大大有助于使这些膜更节能、更具成本效益。这项工作最初将为一名研究生提供培训，结果将整合到本科课程和研究中。通过该项目形成的研究合作将有助于发展加州大学使用尖端技术表征聚合物的能力，为教育和培训研究生和本科生提供更多机会。拟议项目的目标是利用正电子湮没寿命谱(PALS)设计聚酰胺膜分离层。PALS用于在亚纳米尺度上探测材料缺陷、空隙和自由体积，因此对于表征多孔材料非常有用，例如聚合物膜。通过单体间苯二胺与三甲氧基氯的反应合成聚酰胺膜分离层。聚合条件，如单体浓度和聚合时间将改变，以确定各自如何在分子水平上而不是宏观水平上影响聚酰胺分离层自由体积。将在NIST使用PALS系统进行聚酰胺膜分离层的自由体积表征。PALS系统的使用将使人们能够更基本地了解这些聚酰胺膜是如何在分子水平上分离的，以及哪些因素影响这些聚合物膜的自由体积和分离性能。通过了解聚合条件影响聚酰胺自由体积的根本原因，从而在分子水平上影响淡化性能，聚酰胺膜可以被设计成使基于膜的分离过程更加节能和经济。UA和NIST之间的合作将在水处理领域创造高质量的本科生和研究生研究机会，同时促进UA的研究支柱之一，提高为所有人寻求更好的水的标准。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project seeks to build on the water research at The University of Alabama at Tuscaloosa (UA). With a wealth of natural water sources and access to the Gulf of Mexico, Alabama is an ideal location for research in water treatment processes. As such, UA has made water one of its four research pillars to provide better water quality for all people. Polyamide membranes, often called reverse osmosis or RO membranes, are commonly used for seawater desalination. However, their molecular level properties are not well understood. This project will allow researchers from UA to conduct studies at the National Institute of Standards and Technology (NIST) to learn a new technique to characterize the molecular-level properties of water treatment polymer membranes. This research seeks to understand how synthesis conditions affect membrane performance at the molecular level, specifically those involved in seawater desalination. The polymer characterization technique will be of great benefit to make these membranes more energy-efficient and cost-effective. This work will initially provide training for one graduate student, and results will be integrated into undergraduate curriculum and research. The research collaboration formed through this project will help develop capacity at UA to characterize polymers using cutting-edge technology, providing additional opportunities to educate and train graduate and undergraduate students.The goal of the proposed project is to engineer polyamide membrane separation layers by utilizing Positron Annihilation Lifetime Spectroscopy (PALS). PALS is used to probe material defects, voids, and free volume at the sub-nm scale and is therefore useful for characterizing porous materials, such as polymeric membranes. Polyamide membrane separation layers will be synthesized via the reaction between the monomers m-phenylenediamine and trimesoyl chloride. Polymerization conditions such as monomer concentration and polymerization time will be varied to determine how each affects the polyamide separation layer free volume on a molecular level instead of a macroscopic level. Free volume characterization of the polyamide membrane separation layers will be performed using the PALS system at NIST. The use of a PALS system will allow for the development of a more basic understanding of how these polyamide membranes separate on a molecular level and what factors influence the free volume and separation properties of these polymeric membranes. By understanding the fundamental reason why polymerization conditions affect polyamide free volume, and therefore the desalination performance on the molecular level, polyamide membranes can be engineered to make membrane-based separation processes more energy-efficient and cost-effective. The collaboration developed between UA and NIST will generate high-quality undergraduate and graduate research opportunities in the field of water treatment while advancing one of UA's research pillars to raise the bar in the quest for better water for all.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.