Removal of small neutral solutes (SNSs) by reverse osmosis membranes is crucial but challenging. Common consideration of narrowing pore sizes works very little as SNSs have close sizes to the one of water molecules. The most serious drawback of narrowing pore sizes is the reduction of permeance, which dramatically enhances the energy input per volume of permeate water. In this work, an alternative strategy of driving water molecules to reject SNSs is proposed. Using non-equilibrium molecular dynamics simulations, we reveal that inside the nanopores of TpTG multilayers, stable imine-linked covalent organic frameworks, water molecules will preferentially adsorb via the hydrogen bonding interaction. In that way, water molecules in TpTG multilayers other than TpTG themselves can completely reject SNSs, e.g. boric acid. The permeance of TpTG multilayers is excellent as the nanopores are fulfilled with fluidic water. The findings in this work will inspire researchers with an alternative way to design the membranes for SNS removal.

通过反渗透膜去除小的中性溶质 (SNS) 至关重要，但也具有挑战性。由于 SNS 的尺寸与水分子中的一种非常接近，因此通常考虑缩小孔径的作用很小。缩小孔径最严重的缺点是降低了渗透性，这大大提高了每体积渗透水的能量输入。在这项工作中，提出了一种驱动水分子拒绝 SNS 的替代策略。使用非平衡分子动力学模拟，我们揭示了在 TpTG 多层纳米孔内，稳定的亚胺连接的共价有机框架，水分子将通过氢键相互作用优先吸附。这样，TpTG 多层中的水分子除了 TpTG 本身之外，可以完全排斥 SNS，例如硼酸。TpTG 多层膜的渗透性非常好，因为纳米孔充满了流体水。这项工作的发现将启发研究人员用另一种方法设计用于去除 SNS 的膜。