Charge Density Can Enhance Both Transport and Ion Exclusion in Simulated Polystyrenesulfonated Membranes

IF 5.1 1区化学 Q1 POLYMER SCIENCE

Macromolecules Pub Date : 2024-11-26 DOI:10.1021/acs.macromol.4c01565

Ritwick Kali, Scott T. Milner

引用次数: 0

Abstract

Bound charge density is a critical design parameter for tuning water and ion diffusivity in polyelectrolyte membranes. Higher charge density results in increased water uptake and improved diffusivity (transport). However, the impact of bound charge density and consequent water uptake on ion exclusion is crucial for designing membranes with uncompromised selectivity. In this molecular simulation study, we investigate sulfonated polystyrene–polymethylbutylene (PSS–PMB) membranes at different sulfonation levels to explore the effects of bound charge density on water and ion transport and salt exclusion. Remarkably, the equilibrium water uptake per sulfonate group and pore size remain constant irrespective of sulfonation, while the pore morphology transforms significantly. At lower sulfonation levels, the tortuous pores are locally one-dimensional, while higher sulfonation results in locally two-dimensional pores and consequently a 2-fold increase in molecular diffusivity. This morphological change also increases ion concentration at the pore centers, resulting in improvement in salt exclusion of up to 50%.

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电荷密度能增强模拟聚苯乙烯磺化膜的传输和离子排斥能力

结合电荷密度是调整聚电解质膜中水和离子扩散性的关键设计参数。电荷密度越高，吸水量越大，扩散性（传输）越好。然而，束缚电荷密度和随之而来的吸水对离子排阻的影响对于设计具有无损选择性的膜至关重要。在这项分子模拟研究中，我们研究了不同磺化程度的磺化聚苯乙烯-聚甲基丁烯（PSS-PMB）膜，以探索结合电荷密度对水和离子传输以及排盐的影响。值得注意的是，无论磺化程度如何，每个磺酸盐基团的平衡吸水率和孔径都保持不变，而孔隙形态却发生了显著变化。磺化程度较低时，曲折的孔隙局部为一维，而磺化程度较高时，孔隙局部为二维，因此分子扩散性增加了 2 倍。这种形态变化还增加了孔隙中心的离子浓度，使排盐性提高了 50%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Macromolecules 工程技术-高分子科学

CiteScore

9.30

自引率

16.40%

发文量

942

审稿时长

2 months

期刊介绍： Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.