Friction plays a pivotal role in many phenomena of physical chemistry and has long been in the focus of research thereof. As a crucial parameter, frictions in membranes’ inner and/or outer surface can be minimized to reduce solvent inlet pressure and enlarge inner pore fluid flux, ideally reaching near frictionless transport of water at nanoscale. Inspired by the leaf structure of Tillandsia, a porous membrane with a rough surface and a hydrophilic inlet together with hydrophobic pore channels was designed and fabricated, based on covalent organic frameworks (COFs). Combined with COFs’ inherent highly oriented pore structures, the as-made asymmetric membranes through chemical etching can minimize the solvent critical intrusion pressure and enable inner pore low friction water transport. Ultimately, obtained COF membranes succeeded in trapping fog from air and achieved a water harvesting rate (WHR) of 1570 mg cm-2 h-1, together with small molecular pollutants filtrated off in the meantime. Intriguingly, the synthesized asymmetric COF membranes illustrated unidirectional low friction water collecting and transporting features, the successful imitation of T. macdougallii. This work presents a practical strategy to construct functional porous membranes for low friction water collection and transport, and created a model paradigm to design fluid transporting pore channels.

中文翻译：

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受 Tillandsia 启发的不对称共价有机框架膜，用于单向低摩擦水收集


摩擦在许多物理化学现象中起着举足轻重的作用，长期以来一直是其研究的重点。作为一个关键参数，膜内表面和/或外表面的摩擦可以最小化，以降低溶剂入口压力并增加内孔流体通量，理想情况下可以达到纳米级近乎无摩擦的水传输。受 Tillandsia 叶结构的启发，基于共价有机框架 （COFs） 设计和制造了一种具有粗糙表面和亲水入口以及疏水孔通道的多孔膜。结合 COF 固有的高取向孔结构，通过化学蚀刻制成的不对称膜可以最大限度地减少溶剂临界侵入压力，并实现内孔低摩擦水传输。最终，获得的 COF 膜成功地捕获了空气中的雾气，并实现了 1570 mg cm-2 h-1 的集水率 （WHR），同时滤除小分子污染物。有趣的是，合成的不对称 COF 膜说明了单向低摩擦水收集和运输特征，成功模仿了 T. macdougallii。这项工作提出了一种构建用于低摩擦水收集和传输的功能性多孔膜的实用策略，并创建了一个模型范式来设计流体输送孔通道。