Fundamental Water and Ion Transport Properties in Polymers for Membrane Applications

智力优势：根据美国国家工程院的说法，工程学面临的重大挑战之一？为人类提供清洁用水。1开发节能方法，为各种农业、工业和市政应用提供充足的清洁用水，在世界许多地区是一个紧迫而关键的问题。聚合物膜在今天的水净化中发挥着核心作用，由于它们往往比传统技术更节能，它们在水净化中的作用正在增加。从咸水或海水来源净化水的一个关键挑战是去除离子(即海水淡化)。虽然反渗透(RO)膜被广泛用于海水淡化，但还有许多其他基于膜的技术(如正向渗透、电渗析、反向电渗析和膜辅助电容去离子)可以为未来的水净化和发电做出重大贡献。然而，即使是聚合物结构与离子和水传输性能之间的基本关系仍有许多未知之处，这些信息对于合理地为此类应用定制新膜至关重要。因此，该实验研究项目将研究各种聚合物中基本的水和盐的传输特性，以发展结构-性能关系，以帮助设计和优化用于水/离子分离的下一代聚合物膜。对于海水淡化膜材料，拟议计划的一个目标将是了解如何优化聚合物结构，以在保持或降低盐分渗透性的同时增加水的渗透性。该项目将考虑多种材料，以跨越广泛的聚合物结构谱。将研究聚合物电荷、主链刚性、交联度和形态/聚合物结构(例如嵌段共聚物)对水和离子传输性能的影响。研究人员还将描述一价/二价离子浓度对水和离子传输特性的影响。这些研究的结果将提供基本的结构/性能关系，以指导聚合物的合理剪裁，用于海水淡化或其他应用，如上面提到的那些。如果可能，实验结果将与现有模型进行比较。在这方面，现有的模型，如自由体积理论(水和离子扩散性质)和Donnan平衡(离子分配)，将用于数据分析/解释，以构建和验证将实验数据组织成结构/性质关联的系统的基本框架，该框架可用于指导为给定应用选择具有更有利性质轮廓的下一代结构。建议的研究计划非常适合于通过系统的假设驱动的研究来发展基础知识和理解。更广泛的影响：拟议的研究将包括针对学前班到本科生的STEM教育计划，并鼓励来自代表性不足群体的学生参与这些机会。例如，调查人员将组织分离模块在奥斯汀儿童S博物馆的科学星期日上展示，该博物馆接触到广泛的儿童，包括许多拉美裔儿童。他们还将与德克萨斯州聋人学校合作，将听力受损的高中生带到他们的实验室进行课外和暑期研究体验。所有参与拟议研究计划或推广计划的学生都将在制定、实施和分析假设驱动的实验数据时获得关键的研究技能。结果将发表在同行评议的专利文献中，并在适当的时候发表，以便在拟议的计划期间获得的知识将用于指导和教育未来的研究人员。我们还将在科学会议上展示这项工作。整个社会将受益，因为对聚合物结构和水/离子传输特性之间关系的基本了解的提高将使改进的聚合物能够更快地发展用于海水淡化和其他涉及水和离子传输的基于膜的过程。在海水淡化中，这种膜可以为缺水地区的人口提供急需的水，同时降低海水淡化的能源和环境成本。

Intellectual Merit: According to the National Academy of Engineering, one of the ?Grand Challenges for Engineering? is providing access to clean water for mankind.1 The development of energy-efficient methods to provide adequate access to clean water for a variety of agricultural, industrial and municipal applications is an urgent and critical problem in many parts of the world. Polymer membranes play a central role in water purification today, and because they are often more energy-efficient than conventional technologies, their role in water purification is increasing. A key challenge in purifying water from brackish or seawater sources is removal of ions (i.e., desalination). While reverse osmosis (RO) membranes are widely used for desalination, there are a plethora of other membrane-based techniques (e.g., forward osmosis, electrodialysis, reverse electrodialysis, and membrane-assisted capacitive deionization) that could contribute significantly to water purification and power generation in the future. However, much remains unknown about even basic relationships between polymer structure and ion and water transport properties, and such information is critical for rationally tailoring new membranes for such applications. Therefore, the experimental research project will investigate fundamental water and salt transport properties in a variety of polymers to develop structure-property relationships to assist in designing and optimizing next generation polymer membranes for water/ion separations. For desalination membrane materials, one objective of the proposed program will be to understand how polymer structures can be optimized to simultaneously increase water permeability while maintaining or decreasing salt permeability. The project will consider a variety of materials to span a wide polymer structure spectrum. The influence of polymer charge, backbone rigidity, cross-linking, and morphology/polymer architecture (e.g., block copolymers) on water and ion transport properties will be studied. The investigators will also characterize the impact of mono-/divalent ion concentration on water and ion transport properties. Results from these studies will provide fundamental structure/property relations to guide the rational tailoring of polymers for desalination or other applications, such as those mentioned above. When possible, experimental results will be compared with existing models. In this regard, available models, such as free volume theory (for water and ion diffusion properties) and Donnan equilibrium (for ion partitioning), will be used in data analysis/interpretation to construct and validate a systematic, fundamental framework for organizing experimental data into structure/property correlations that can be used to guide selection of next-generation structures with more favorable property profiles for a given application. The proposed research program is well suited for developing fundamental knowledge and understanding through systematic hypothesis-driven studies. Broader Impacts: The proposed study will include STEM education programs for pre-K through undergraduate students, and students from underrepresented groups will be encouraged to participate in these opportunities. For example, The investigators will organize separations modules to be presented at Science Sundays at the Austin Children?s Museum, which reaches a broad spectrum of children, including many children of Hispanic origin. They will also partner with the Texas School for the Deaf to bring hearing-impaired high school students to their laboratories for after-school and summer research experiences. All students engaging in the proposed research program or the outreach programs will gain critical research skills while formulating, conducting, and analyzing data from hypothesis-driven experiments. Results will be published in the peer-reviewed and, when appropriate, patent literature so that the knowledge gained during the proposed program will be available to guide and educate future researchers. We would also present the work at scientific conferences. Society-at-large will benefit because improved fundamental understanding of relationships between polymer structure and water/ion transport properties will enable more rapid development of improved polymers for desalination and other membrane-based processes involving water and ion transport. In desalination, such membranes could provide populations in water-stressed regions with critically needed water while reducing the energy and environmental cost of desalination.