<br>限制和两性离子配体化学对功能化纳米孔离子-离子选择性的影响,Langmuir

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限制和两性离子配体化学对功能化纳米孔离子-离子选择性的影响
Langmuir ( IF 3.7 ) Pub Date : 2024-04-24 , DOI: 10.1021/acs.langmuir.4c00286
Harnoor Singh Sachar ₁ , Everett S Zofchak ₁ , Nico Marioni ₁ , Zidan Zhang ₁ , Venkat Ganesan ₁

Affiliation

结合两性离子化学物质的膜最近已成为促进具有挑战性的离子-离子分离的有希望的候选者。此类膜中的离子传输主要发生在衬有两性离子单体的水合纳米孔中。为了阐明此类材料中离子-离子选择性的物理原理，我们对接枝了磺基甜菜碱甲基丙烯酸酯分子的模型纳米孔中的卤化钠传输进行了分子动力学模拟。我们的结果表明，在功能化和非功能化纳米孔中，较小的离子倾向于驻留在孔中心附近，而较大的离子倾向于驻留在孔壁附近。相对于水溶液中的盐，在未功能化的纳米孔内观察到较大阴离子的选择性传输增强。在用两性离子 (ZI) 功能化纳米孔时，孔内阴离子分布曲线的差异以及阴离子-ZI 相互作用的差异导致较大阴离子相对于较小阴离子的减慢。增加 ZI 接枝密度会加剧这些影响，进一步促进较小阴离子的选择性转运。我们的结果表明，通过使用 ZI 含量足够高的纳米多孔膜可以实现对大阴离子的选择性，以促进离子/水分配到孔中，同时保留未功能化孔的特征趋势，以促进较大阴离子的更快传输。另一方面，可以通过将孔内的 ZI 含量作为目标来实现对较小阴离子的选择性，该 ZI 含量足够高以显着减慢大阴离子的传输，但又不足以阻碍离子/水分子分配到孔中，因为位阻效应。

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Impact of Confinement and Zwitterionic Ligand Chemistry on Ion–Ion Selectivity of Functionalized Nanopores

Membranes incorporating zwitterionic chemistries have recently emerged as promising candidates for facilitating challenging ion–ion separations. Transport of ions in such membranes predominantly occurs in hydrated nanopores lined with zwitterionic monomers. To shed light on the physics of ion–ion selectivity underlying such materials, we conducted molecular dynamics simulations of sodium halide transport in model nanopores grafted with sulfobetaine methacrylate molecules. Our results reveal that in both functionalized and unfunctionalized nanopores smaller ions prefer to reside near the pore center, while the larger ions tend to reside near the pore walls. An enhancement in the selective transport of larger anions is observed within the unfunctionalized nanopores relative to that in salt-in-water solutions. Upon functionalization of the nanopores with zwitterions (ZIs), the disparities in the anionic distribution profiles within the pores coupled with differences in the anion-ZI interactions result in a slowdown of larger anions relative to smaller anions. Increasing the ZI grafting density exacerbates these effects, further promoting the selective transport of smaller anions. Our results suggest that selectivity toward large anions can be realized by using nanoporous membranes with ZI content that is high enough to facilitate ion/water partitioning into the pores while preserving the characteristic tendency of the unfunctionalized pores to facilitate faster transport of the larger anions. On the other hand, selectivity toward smaller anions can be achieved by targeting ZI content within the pores that is high enough to significantly slow down the transport of large anions but not high enough to hinder the partitioning of ions/water molecules into the pore due to steric effects.

更新日期：2024-04-24

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