AbstractReverse osmosis (RO) membranes are becoming popular as energy saving and environmentally friendly materials for the desalination of water. Toward the rational design of RO membranes, we performed contrast-variation neutron scattering measurements and atomistic molecular dynamics (MD) simulations on polyamide/water systems with various water contents and deuteration ratios. The experimental and computational structure factors showed good agreement for all the systems examined. The structure of the water-rich polyamide/water system obtained from MD calculation showed that the water clusters are well connected to each other, and a relatively large number of water molecules are present at a distance over 3 Å from the polyamide. The partial radial distribution functions were calculated, and strong interactions were observed between water and the carboxyl group in polyamide. Thus, the water permeability of the RO membrane can be expected to improve when more carboxyl groups are introduced. In addition, the polyamide–polyamide interaction was found to be equal to or smaller than the polyamide–water interactions and relatively weak in the water-rich system.Reverse osmosis membranes have been playing a main role for the desalination of water in the world. Hydration structure of polyamide functional layer of the membrane was studied via neutron scattering and atomistic molecular dynamics simulations. Experimental and computational structure factors, S(Q), of the polyamide/water system showed good agreement. Water clusters in water-rich system were well connected to each other and formed channel-like structure. Polyamide–water interactions and polyamide-polyamide interactions, which are thought to be important to enhance the performance of the membranes, were examined in detail.

中文翻译：

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通过中子散射和原子分子模拟研究反渗透膜的水化结构

摘要 反渗透（RO）膜作为一种节能环保的海水淡化材料，越来越受到人们的青睐。为了合理设计 RO 膜，我们对具有各种含水量和氘化比的聚酰胺/水系统进行了对比度变化中子散射测量和原子分子动力学 (MD) 模拟。实验和计算结构因素对所有检查的系统都显示出良好的一致性。MD计算得到的富水聚酰胺/水体系结构表明，水团簇相互连接良好，在距离聚酰胺3 Å以上的位置存在较多的水分子。计算了部分径向分布函数，在聚酰胺中观察到水和羧基之间有很强的相互作用。因此，当引入更多的羧基时，可以预期 RO 膜的透水性会提高。此外，发现聚酰胺-聚酰胺相互作用等于或小于聚酰胺-水相互作用，并且在富水系统中相对较弱。反渗透膜在世界上的海水淡化中一直发挥着主要作用。通过中子散射和原子分子动力学模拟研究了膜的聚酰胺功能层的水合结构。聚酰胺/水系统的实验和计算结构因子 S(Q) 显示出良好的一致性。富水系统中的水团簇相互连通，形成通道状结构。