Influence of Membrane Permittivity on Charge Regulation of Weak Polyelectrolytes End-Tethered in Nanopores
Influence of Membrane Permittivity on Charge Regulation of Weak Polyelectrolytes End-Tethered in Nanopores
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DOI：
10.1021/acs.macromol.2c01391
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发表时间：
2022-09
期刊：
影响因子：
5.5
通讯作者：
Shiyi Qin;Rikkert J. Nap;Kai Huang;I. Szleifer
中科院分区：
文献类型：
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作者：
Shiyi Qin;Rikkert J. Nap;Kai Huang;I. Szleifer
由弱聚电解质功能化的人工纳米孔是一类有趣而重要的刺激响应型纳米流体器件。到目前为止，支撑纳米孔表面的介电性质对纳米孔行为的影响在很大程度上还没有被探索。在这里，我们从理论上研究了溶剂和纳米孔表面的介电失配对纳米孔内弱聚电解质刷电荷调节的影响。我们的方法是基于分子理论，该理论明确地结合了分子组织、物理相互作用和化学平衡之间的耦合。它进一步扩展到既考虑纳米孔支撑面的介电性质，也考虑纳米孔溶剂和聚合物层的介电性质。我们发现，表面极化对末端拴在纳米孔内壁的弱聚电解质的电荷和结构起着至关重要的调节作用。同样，表面极化也会影响纳米孔的纳米尺度输运。结果表明，纳米孔膜的介电性质不同会导致弱聚电解质可电离基团周围的局部离子分布和静电势发生很大变化，从而同时改变纳米孔内聚电解质层的电荷和结构。我们的定量方法系统地揭示了各种内部和外部因素，如本体盐浓度、聚合物接枝密度和聚合物长度如何影响表面极化及其对聚电解质层电荷等性质的影响。在特定条件下，我们报告了运输货物对涂覆聚电解质的纳米孔表面介电性质的变化的高度敏感性。
Artificial nanopores functionalized with weak polyelectrolytes are an interesting and important class of stimuli-responsive nanofluidic devices. So far, the effects of the dielectric properties of the supporting nanopore surface on the behavior of the nanopore are largely unexplored. Here, we theoretically investigate the influence that the dielectric mismatch between solvent and nanopore surface has on the charge regulation of weak polyelectrolyte brushes inside the nanopore. Our approach is based on a molecular theory that explicitly incorporates the coupling between molecular organization, physical interactions, and chemical equilibrium. It is further extended to consider both the dielectric properties of the supporting surface of the nanopore as well as those of the nanopore solvent and polymer layer. We find that the surface polarization plays a crucial role in modulating the charge and structure of the weak polyelectrolytes that are end-tethered to the inner wall of the nanopore. Likewise, the surface polarization influences the nanoscale transport through the nanopore. We demonstrate that different dielectric properties of the nanopore membrane can result in large changes in the local ion distribution and electrostatic potential around the ionizable groups of the weak polyelectrolytes, which simultaneously alter the charge and structure of the polyelectrolyte layer inside the nanopore. Our quantitative approach systematically reveals how various intrinsic and external factors such as bulk salt concentration, polymer grafting density, and polymer length influence the surface polarization and its effects on properties such as the charge of the polyelectrolyte layer. For specific conditions, we report a high sensitivity of translocating cargoes to the changes in the dielectric properties of the polyelectrolyte-coated nanopore surface.