Novel Nanostructured Membranes for Gas Separations

用于气体分离的新型纳米结构膜用于气体对分离的聚合物膜表现出气体选择性和气体通量之间的反向关系。将两者最大化将是一个重大的进步。将多孔无机材料的选择性分离性能与聚合物的可加工性相结合的想法已经产生了几个进展。然而，这种膜的性能似乎已经达到了一个平台期，需要一种新的方法来实现基于膜的气体分离的革命性突破。PI发现，通过添加少量的多孔纳米颗粒，可以在纳米尺度上设计出由原本不相容的聚合物构成的膜。目前用于气体分离的混合基质膜(MMM)的主要限制是气体通量低，这主要是由于容纳多孔添加剂所需的膜厚度(几十微米)。颗粒直径为60 nm的胶体ZIF将使选择性聚合物层厚度达到亚微米，与逐层形态相比，基质-液滴几何结构将使界面表面积增加50至100倍，在保持优异渗透选择性的同时大幅增加通量。为了充分利用这种新的膜结构，还将深入了解控制该结构的热力学和动力学因素。将无机分子筛的选择性分离性能与聚合物的可加工性相结合，形成混合基质膜(MMM)，其中包括金属有机骨架(MOF)和沸石咪唑骨架(ZIF)等多孔添加剂的引入。这些添加剂的有机-无机混合性质改善了与聚合物基质的界面接触，使MMM能够实现非常高的负载。PI提出了一种独特的膜结构，由原本不相容的聚合物的混合物组成，可以通过添加少量ZIF在纳米级进行工程设计。通过选择具有适当界面/表面张力的组成材料，ZIF纳米颗粒定位于聚合物之间的界面。这具有使高性能不相容聚合物相容的优点，从而极大地扩展了可利用的聚合物组合的数量。这项拟议的研究将开发由一种高选择性聚合物的薄而连续的丝带嵌入第二种高渗透聚合物的不连续基质中的膜，这有点类似于美国农业部优质牛肉中的大理石花纹。这种结构将显著提高膜的性能，特别是通过在较低的添加剂负荷下增加通量和选择性，从而降低成本。这一关于能源和环境的项目包括许多任务，这些任务将导致膜科学和新型纳米材料领域的研究和多层次教育相结合。用膜替代能量密集型分离可以节省经济成本。这种水平的结构控制也可能对燃料电池应用和其他分离有用。此外，与研究活动同时进行的强有力的教育内容将吸引研究生和本科生以及来自代表性不足群体和妇女的学生。学生在这个项目中获得的技能将增强他们在膜工程、纳米技术、能源和材料科学领域的职业准备。我们还致力于高中学生的研究经验，我们预计这个项目也将通过教育我们的高中教师和学生来影响整个社区。签名名称：罗斯玛丽·D·韦森标题：项目主任项目：化学和生物分离日期：2014年4月

Ferraris, John 1403950 Novel Nanostructured Membranes for Gas Separations Polymer membranes for gas pair separations exhibit an inverse relationship between gas selectivity and gas flux. Maximizing both would be a significant advance. The idea of combining the selective separation properties of porous inorganic materials with the processability of polymers has resulted in several advances. Nevertheless, it appears that the performance of such membranes has reached a plateau, and a new approach will be needed to achieve a revolutionary breakthrough in membrane-based gas separations. The PIs have discovered that membranes constructed from otherwise immiscible polymers can be engineered at the nanoscale through the addition of small amounts of porous nanoparticles. The major limitation with current mixed matrix membranes (MMMs) for gas separations is their low gas flux, primarily due to the membrane thickness (several tens of micrometers) that is required to accommodate the porous additives. Colloidal ZIFs with particle diameters of 60 nm will enable the selective polymer layer to be submicrometer in thickness, and the matrix-droplet geometry will increase the interfacial surface area by 50 to 100X compared to a layer-by-layer morphology, greatly increasing flux while maintaining superior permselectivity. In order to fully utilize this novel membrane architecture, a thorough understanding of the thermodynamic and kinetic factors that control the structure will also be researched. Combining the selective separation properties of inorganic molecular sieves with the processability of polymers to form mixed-matrix membranes (MMMs) has resulted in several advances including the incorporation of porous additives such as metal organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs). The organic-inorganic hybrid nature of these additives has afforded improved interfacial contact with the polymer matrix, enabling very high loadings in the MMMs. The PIs propose a unique membrane architecture comprising blends of otherwise immiscible polymers that can be engineered at the nanoscale through the addition of small amounts of ZIFs. By choosing component materials with appropriate interfacial/surface tensions, the ZIF nanoparticles localize at the interface between the polymers. This has the advantage of compatibilizing high performance immiscible polymers thus greatly expanding the number of polymer combinations that can be utilized. The proposed research will develop membranes comprising thin, continuous ribbons of a highly selective polymer embedded in a discontinuous matrix of a second, highly permeable polymer, somewhat akin to the marbling in USDA Prime Beef. Such architectures will significantly improve the performance of membranes, especially by increasing flux and selectivity at lower additive loadings, thus reducing cost. This project on energy and the environment includes numerous tasks that will lead to the integration of research and multilevel education in the area of membrane science and novel nanomaterials. The replacement of energy intensive separations with membranes could result in economic savings. This level of structural control could also be potentially useful for fuel cell applications and other separations. Additionally, the strong educational component coinciding with the research activities will engage students at both the graduate and undergraduate levels, as well as students from underrepresented groups and women. The skills acquired by students during this project will enhance their preparation for careers in membrane engineering, nanotechnology, energy, and materials science. We are also committed to high school student research experiences and we anticipate that this project will also impact the community at large by educating our high school teachers and students.SIGNATURE Name: Rosemarie D. Wesson Title: Program Director Program: Chemical and Biological Separations DATE: April 2014