Layer-by-layer polymer assemblies as size-selective gas separation membranes

1403686 wilhitteexas工程实验站提议的研究工作通过研究能够结合高纯度和高气体分离率的聚合物涂层，解决了对低成本气体净化膜材料的需求。研究人员建议将膜基质交替浸入含有正电荷和负电荷聚合物的水浴中，一次一层地生长聚合物薄膜。这导致了一层接一层（LbL）薄膜的生长。最近，pi已经证实，使用由聚丙烯酸（PAA）和支化聚乙烯胺（PEI）溶液组装的LbL膜可以实现氢-二氧化碳和氢-氮选择性的数量级提高。提出的工作利用这些最近的结果来确定能够尺寸选择性气体分离的突破性聚合物材料，以满足多种可持续能源需求。pi建议使用LbL组装技术来操纵膜结构，从而调整传输性能和膜耐久性。提高传输性能和膜耐久性将通过以下两方面的结合来实现：(i)旨在表征聚阴离子和聚阳离子结合程度的基本材料分析，并将其与机械和纳米结构特性联系起来；（ii）瞬态气体渗透测量，以获得通过LbL膜的单个气体渗透率的精确测量。研究工作不仅集中在LbL膜的氢-二氧化碳分离能力上，而且还将基本概念应用于生物燃料（乙醇）脱水和天然气处理的定制膜。因此，开发的材料可能会对能源工业产生重大而直接的影响。PI的团队在研究生和本科生阶段持续参与与社会相关的研究课题。这项工作的各个方面也将纳入多个正在进行的K-12外展计划目前在德州农工大学。PI团队还计划利用流行的HexBug Nano玩具开发在线学习练习，并将在网上传播。这些外联工作将作为开发教学工具的平台，向非stem受众说明扩散和相关的运输现象概念。

1403686WilhiteTexas Engineering Experiment StationThe proposed research effort addresses the need for low-cost membrane materials for gas purification by investigating polymer coatings capable of combining high rates of gas separation with high purity. The researchers propose growing polymer films one layer at a time by alternately dipping the membrane substrate into a water bath containing positively- and negatively-charged polymers. This results in the growth of a Layer-by-Layer (LbL) thin film. Recently the PIs have confirmed that order-of-magnitude improvements in hydrogen-carbon dioxide and hydrogen-nitrogen selectivity may be achieved using LbL films assembled from polyacrylic acid (PAA) and branched polyethylemine (PEI) solutions. The proposed work leverages these recent results to identify breakthrough polymeric materials capable of size-selective gas separations to meet multiple sustainable energy needs. The PIs propose to use the LbL assembly technique to manipulate membrane structure, in turn tuning both transport properties and membrane durability. Increased transport properties and membrane durability will be achieved through a combination of (i) fundamental materials analysis aimed at characterizing the extent of polyanion and polycation bonding and relating it to mechanical and nanostructural properties, and (ii) transient gas permeation measurements for obtaining precise measurements of individual gas permeabilities through the LbL membrane. The research efforts are focused not only upon proven hydrogen-carbon dioxide separation capability of LbL films, but also applying fundamental concepts to tailored membranes for biofuel (ethanol) dehydration and natural gas processing. Therefore, materials developed may have significant and immediate impact upon the energy industry. The PI's team has ongoing engagement of underrepresented groups at the graduate and undergraduate levels in socially relevant research topics. Aspects of this work will also be incorporated into multiple ongoing K-12 outreach programs present at Texas A&M University. The PI team plan to also develop online learning exercises utilizing the popular line of HexBug Nano toys, which will be disseminated online. These outreach efforts will be leveraged as a platform for developing teaching tools for illustrating diffusion and related transport phenomena concepts to non-STEM audiences.