Abstract Covalent organic frameworks (COFs), with their inherent merits of specific pore size and uniform channels, have been extensively employed to produce nanofiltration (NF) membranes. However, COF-based NF towards precise separations, especially for ion separations, are often unsatisfying due to the intercrystalline defects in selective layers. Herein, a pressure-modulated synthesis method has been explored to prepare crystalline and defect-free COF membranes on seeded substrates for fast NF. Amine and aldehyde solutions are separately placed with a level interval to create vertical hydraulic pressure, which can regulate the mobility of the amine monomers and thus results in the self-repairing of defects in the COF planes and remediation of intercrystalline gaps. The abundant nucleation sites on seeded substrates promote the confined growth of COF crystallites in top layers, leading to an ultrathin selective layer with improved permeance. The resultant COF membrane shows tight methyl orange (~90.4%) and Na2SO4 (~63.6%) rejections with a pronounced water permeance of up to ~44.2 L m−2 h−1 bar−1, which is ~2–10 times higher than other NF membranes with similar rejections. This pressure-modulated synthetic strategy establishes not only the self-repairing synthesis of COFs but also the controllable preparation of defect-free COF-based NF membranes, thus enabling precise and fast separation of molecules and ions.

中文翻译：

---

用于高通量纳滤的自修复共价有机骨架 (COF) 的压力调节合成

摘要 共价有机骨架 (COF) 具有特定孔径和均匀通道的固有优点，已被广泛用于生产纳滤 (NF) 膜。然而，由于选择性层中的晶间缺陷，基于 COF 的 NF 对精确分离，尤其是对于离子分离而言，通常并不令人满意。在此，研究人员探索了一种压力调节合成方法，以在用于快速 NF 的种子基质上制备结晶和无缺陷的 COF 膜。胺和醛溶液以水平间隔分开放置，以产生垂直液压，这可以调节胺单体的流动性，从而导致COF平面缺陷的自修复和晶间间隙的修复。晶种基底上丰富的成核位点促进了 COF 微晶在顶层的受限生长，从而形成具有改善渗透性的超薄选择性层。所得 COF 膜显示出紧密的甲基橙 (~90.4%) 和 Na2SO4 (~63.6%) 截留率，显着的水渗透率高达 ~44.2 L m-2 h-1 bar-1，高 ~2-10 倍与具有类似截留率的其他 NF 膜相比。这种压力调节合成策略不仅建立了 COF 的自修复合成，而且建立了无缺陷的基于 COF 的 NF 膜的可控制备，从而实现了分子和离子的精确和快速分离。6%) 具有高达 ~44.2 L m-2 h-1 bar-1 的显着水渗透率的截留率，比具有类似截留率的其他 NF 膜高 ~2-10 倍。这种压力调节合成策略不仅建立了 COF 的自修复合成，而且建立了无缺陷的基于 COF 的 NF 膜的可控制备，从而实现了分子和离子的精确和快速分离。6%) 具有高达 ~44.2 L m-2 h-1 bar-1 的显着水渗透率的截留率，比具有类似截留率的其他 NF 膜高 ~2-10 倍。这种压力调节合成策略不仅建立了 COF 的自修复合成，而且建立了无缺陷的基于 COF 的 NF 膜的可控制备，从而实现了分子和离子的精确和快速分离。