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

标题：CBET-EPSRC可调和膜开发的一种改变游戏规则的方法：由耐溶剂材料支持的新型共价有机框架活性层1706219码头表面和地下水可以通过纳滤净化到饮用水质量标准，这是一种依靠膜作为物理屏障从水中去除污染物的压力驱动过程。这种膜允许水以比溶解和/或悬浮溶质更快的速度通过其纳米尺寸的孔，从而使通过膜的水得到净化。为了获得更高的水质，更有选择性的反渗透膜具有亚纳米级的孔，这需要更高的应用压力来促进水在膜上的传输。膜对水的渗透性和对污染物的不渗透性之间通常存在权衡：较小的孔径保留了更广泛的污染物范围，但减少了单位时间的水通量和/或增加了能源消耗；相反，较大的孔径导致较少的污染物截留率，但较高的透水率或较低的能源消耗。最先进的膜是由聚合物制成的，对于聚合物，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，所以孔的大小在分子水平上不容易控制。由于生物污染、机械压实和化学降解的负面影响，目前的膜寿命有限。生物污染是有机污染物和营养物质沉积在膜上的结果，随后生物膜的生长为随后的水透过膜创造了障碍；聚合物压实导致膜的无定形部分的孔收紧，从而降低了水的渗透率；化学降解是在清洗污染的膜期间使用苛刻的化学品而加剧的过程，最终导致对污染物的更高渗透率。为了解决这些问题，该项目将开发新型膜，使其能够在分子水平上设计孔的大小和形状，并加入耐污染的化学官能团。该项目利用了一种新的界面聚合工艺，即在高表面积的聚合物薄膜中合成共价有机骨架。与其他聚合物材料不同，这些骨架是高度结晶的，具有明确的表面化学和规则的孔结构，这种规律性使分子级设计成为可能，这反过来又将允许特定溶质的最佳保留以及膜的高透水率。还可以对骨架进行修饰，以加入防污表面化学物质并减小孔径。这一合作项目的关键进展是开发了薄的活性共价有机骨架层，与在聚合过程和膜清洗过程中使用的溶剂中稳定的聚合物载体相协调。该项目的工作范围包括合成具有不同组成单元的新型膜，通过改变共价有机骨架来调节孔径和表面化学，以及鉴定溶剂稳定的载体介质。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，以控制共价有机骨架和载体之间的界面。所得到的膜将在模型污染物的水溶液中进行性能测试。在美国和英国机构间协议的推动下，这一国际合作将来自两个国家的膜和聚合物合成专家聚集在一起，开发这种新型膜，同时建立一个国际研究网络，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.