Zuo Hongyu, Lyu Baokang, Yao Jiaao, Long Wenhua, Shi Yu, Li Xinghao, Hu Huawei, Thomas Arne, Yuan Jiayin, Hou Bo, Zhang Weiyi, Liao Yaozu
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, China.
Department of Chemistry, Functional Materials, Technical University of Berlin, Sekretariat BA 2, 4010623, Hardenbergstr, Berlin, Germany.
Adv Mater. 2024 Apr;36(16):e2305755. doi: 10.1002/adma.202305755. Epub 2024 Jan 24.
Gradients play a pivotal role in membrane technologies, e.g., osmotic energy conversion, desalination, biomimetic actuation, selective separation, and more. In these applications, the compositional gradients are of great relevance for successful function implementation, ranging from solvent separation to smart devices; However, the construction of functional gradient in membranes is still challenging both in scale and directions. Inspired by the specific function-related, graded porous structures in glomerular filtration membranes, a general approach for constructing gradient covalent organic framework membranes (GCOMx) applying poly (ionic liquid)s (PILs) as template is reported here. With graded distribution of highly porous covalent organic framework (COF) crystals along the membrane, GCOMx exhibts an unprecedented asymmetric solvent transport when applying different membrane sides as the solvent feed surface during filtration, leading to a much-enhanced flux (10-18 times) of the "large-to-small" pore flow comparing to the reverse direction, verified by hydromechanical theoretical calculations. Upon systematic experiments, GCOMx achieves superior permeance in nonpolar (hexane ≈260.45 LMH bar) and polar (methanol ≈175.93 LMH bar) solvents, together with narrow molecular weight cut-off (MWCO, 472 g mol) and molecular weight retention onset (MWRO, <182 g mol). Interestingly, GCOMx shows significant filtration performance in simulated kidney dialysis, revealing great potential of GCOMx in bionic applications.
梯度在膜技术中起着关键作用，例如渗透能转换、海水淡化、仿生驱动、选择性分离等等。在这些应用中，成分梯度对于成功实现功能至关重要，涵盖从溶剂分离到智能设备等领域；然而，在膜中构建功能梯度在规模和方向上仍然具有挑战性。受肾小球滤过膜中与特定功能相关的分级多孔结构的启发，本文报道了一种以聚（离子液体）（PILs）为模板构建梯度共价有机框架膜（GCOMx）的通用方法。由于高度多孔的共价有机框架（COF）晶体在膜中呈分级分布，GCOMx在过滤过程中将不同的膜面作为溶剂进料表面时，表现出前所未有的不对称溶剂传输，与反向相比，“大到小”孔流的通量显著提高（10 - 18倍），这通过流体力学理论计算得到验证。经过系统实验，GCOMx在非极性（己烷≈260.45 LMH bar）和极性（甲醇≈175.93 LMH bar）溶剂中均具有优异的渗透率，同时具有较窄的分子量截留值（MWCO，472 g/mol）和分子量保留起始值（MWRO，<182 g/mol）。有趣的是，GCOMx在模拟肾脏透析中表现出显著的过滤性能，揭示了GCOMx在仿生应用中的巨大潜力。
