Emerged as a new class of nanoporous materials, porous organic cages (POCs) possess salient features of solvent processability and water stability; thus, they are envisioned as promising membrane materials for water desalination. In this study, we propose a simulation protocol to construct atomic models of amorphous POC membranes and examine their desalination performance. Five membranes (AC1, AC2, AC3, AC16, and AC17) with similar cage structure but different periphery groups are considered. All the five membranes exhibit 100% salt rejection. In contrast to crystalline CC1 membrane, which is impermeable to water, AC1 has a water permeability P_w of 3.6 × 10^–8 kg·m/(m²·h·bar). With increasing interconnected pores in AC2, AC3, AC16, and AC17, P_w increases. Due to the existence of hydroxyl groups in CC17 cages, AC17 exhibits the highest P_w of 3.17 × 10^–7 kg·m/(m²·h·bar), which is higher than in commercial reverse osmosis membranes. Significantly, P_w is found to enhance in mixed AC3/AC17 and AC16/AC17 membranes with up to one-fold enhancement. The enhanced P_w is attributed to the counterbalance between water sorption and diffusion. This simulation study provides the bottom-up insights into the dynamics and structure of water in amorphous POC membranes, highlights their potential use for water desalination, and suggests a unique strategy to enhance desalination performance by tuning the composition of mixed POC membranes.

中文翻译：

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用于水脱盐的非晶多孔有机笼式膜

作为一种新型的纳米多孔材料，多孔有机笼（POC）具有溶剂加工性和水稳定性的显着特征。因此，可以预见它们是用于海水淡化的有前途的膜材料。在这项研究中，我们提出了一种模拟协议，以构建无定形POC膜的原子模型并检查其脱盐性能。五个具有相似笼形结构但外围组不同的膜（AC1，AC2，AC3，AC16和AC17）被考虑。所有五个膜均表现出100％的脱盐率。与不透水的结晶CC1膜相反，AC1的透水率P _w为3.6×10 ^–8 kg·m /（m ² ·h·bar）。随着AC2，AC3，AC16和AC17中相互连通的孔的增加，P _w增加。由于CC17笼子中存在羟基，因此AC17的最高P _w为3.17×10 ^–7 kg·m /（m ² ·h·bar），高于商业反渗透膜。显着地，发现P _w在混合的AC3 / AC17和AC16 / AC17膜中增强达一倍。增强的P _{w ^}归因于水吸收和扩散之间的平衡。该模拟研究提供了对无定形POC膜中水的动力学和结构的自下而上的见解，突出了其在水脱盐中的潜在用途，并提出了通过调整混合POC膜的组成来提高脱盐性能的独特策略。