CBET-EPSRC A Game-Changing Approach for Tunable Membrane Development: Novel Covalent Organic Framework Active Layers Supported by Solvent Resistant Materials

职务名称：CBET-EPSRC一种改变游戏规则的可调膜开发方法：由耐溶剂材料支撑的新型共价有机框架活性层1706219码头地表水和地下水可以通过纳滤净化到饮用水质量标准，纳滤是一种压力驱动的过程，依赖于膜作为物理屏障来去除水中的污染物。与溶解和/或悬浮的溶质相比，该膜允许水以更高的速率通过其纳米尺寸的孔，导致通过膜的水的净化。为了实现更高的水质，更有选择性的反渗透膜具有亚纳米孔，这需要更高的压力来促进水穿过膜的传输。在膜对水的渗透性与对污染物的不渗透性之间存在一般的权衡：较小的孔径保留更宽范围的污染物，但降低每单位时间的水通过量和/或增加能量消耗;相反，较大的孔径导致较少的污染物截留，但较高的水渗透性或较低的能量消耗。现有技术的膜由聚合物制成，聚合物链之间的空间充当过滤污染物的孔。由于这些孔是通过聚合物链的三维排列形成的，因此不容易在分子水平上控制孔径。由于生物污染、机械压实和化学降解的负面影响，目前的膜具有有限的寿命。生物结垢是有机污染物和营养物在膜上的沉积以及随后生物膜的生长的结果，生物膜的生长为随后的水渗透通过膜产生屏障;聚合物压实导致膜的无定形部分中的孔收紧，这导致水渗透性降低;并且化学降解是在清洁污染的膜期间使用刺激性化学品而加剧的过程，其最终导致对污染物的更高渗透性。为了解决这些问题，该项目将开发新型膜，使孔径和形状的分子水平的设计，并结合防污化学官能团。该项目利用了一种新的界面聚合工艺，在高表面积的聚合物薄膜中合成共价有机框架。与其他聚合物材料不同，这些框架是高度结晶的，具有明确的表面化学和规则的孔结构，这种规则性使得能够进行分子水平的设计，这反过来将允许优化特定溶质的保留，并结合跨膜的高透水性。还可以对框架进行改性以并入防污表面化学并减小孔径。该合作项目的关键进展是开发薄的活性共价有机框架层，该框架层与聚合物载体相结合，该聚合物载体在聚合过程和膜清洁过程中使用的溶剂中稳定。该项目的工作范围包括合成具有各种结构单元的新型膜，通过改变共价有机框架来调整孔径和表面化学，以及确定溶剂稳定的支持介质。各种表面分析技术将用于所得膜的物理化学表征，以及界面聚合过程的优化，以控制共价有机框架和支持物之间的界面。将用模型污染物的水溶液测试所得膜的性能。这种国际合作，由美国和英国之间的机构间协议促进，来自两个国家的膜和聚合物合成专家聚集在一起，开发这种新的膜，同时建立国际研究网络，并为学生提供独特的国际教育机会。

Title: CBET-EPSRC A Game-Changing Approach for Tunable Membrane Development: Novel Covalent Organic Framework Active Layers Supported by Solvent Resistant Materials 1706219 Marinas Surface and groundwater may be purified to drinking water quality standards via nanofiltration, a pressure-driven process which relies on a membrane as a physical barrier to remove contaminants from water. The membrane allows water to pass through its nanometer size pores at a higher rate compared to dissolved and/or suspended solutes, resulting in purification of the water that passes through the membrane. To achieve even higher water quality, more selective reverse osmosis membranes have sub-nanometer pores, which require higher applied pressure to facilitate water transport across the membrane. There is a general trade-off between permeability of the membrane to water versus impermeability to contaminants: smaller pore sizes retain a broader range of contaminants but decrease water throughput per unit time and/or increases energy consumption; in contrast, larger pore sizes lead to less contaminant rejection but higher water permeability or lower energy consumption. State of the art membranes are made from polymers, for which the spaces between the polymeric chains act as the pores that filter the contaminants. As these pores are formed via the three-dimensional arrangement of polymer chains, the pore size is not easily controlled on a molecular level. Current membranes have a limited lifetime, due to the negative effects of biofouling, mechanical compaction, and chemical degradation. Biofouling is a result of the deposition of organic contaminants and nutrients on the membrane and the subsequent growth of a biofilm that creates a barrier for subsequent water permeation through the membrane; polymer compaction results in pore tightening in the amorphous portion of membranes that leads to reduced water permeability; and chemical degradation is a process exacerbated by the use of harsh chemicals during cleaning of fouled membranes that ultimately results in higher permeability to contaminants. To address these concerns, this project will develop novel membranes that enable a molecular-level design of pore size and shape and the incorporation of fouling-resistant chemical functional groups. The project capitalizes upon a new interfacial polymerization process that synthesizes covalent organic frameworks in a high-surface area thin polymeric film. Unlike other polymeric materials, these frameworks are highly crystalline with well-defined surface chemistry and a regular pore structure, this regularity enables molecular level design, which in turn will allow for optimized retention of particular solutes combined with high water permeability across the membrane. The frameworks could also be modified to incorporate anti-fouling surface chemistry and to decrease pore size. The key advance of this collaborative project is to develop the thin active covalent organic framework layer in concert with a polymeric support that is stable in the solvents used for the polymerization process and during membrane cleaning. The project scope of work includes synthesis of novel membranes with various building blocks, tuning of pore size and surface chemistry by altering the covalent organic framework, and the identification of solvent stable support media. Various surface analysis techniques will be used for the physicochemical characterization of the resulting membranes, and optimization of the interfacial polymerization process to control the interface between the covalent organic framework and the support. The resulting membranes will be tested for performance with aqueous solutions of model contaminants. This international collaboration, facilitated by an inter-agency agreement between the U.S. and U.K., brings together membrane and polymer synthesis experts from two countries to develop this new class of membranes while building an international research network and providing students with a unique international educational opportunity.