Unexpected Two-Stage Swelling of Weak Polyelectrolyte Brushes with Divalent Counterions,ACS Macro Letters

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Unexpected Two-Stage Swelling of Weak Polyelectrolyte Brushes with Divalent Counterions
ACS Macro Letters ( IF 5.1 ) Pub Date : 2024-08-22 , DOI: 10.1021/acsmacrolett.4c00421
David Beyer ₁ , Christian Holm ₁

Affiliation

We use particle-based, coarse-grained simulations to study the influence of divalent counterions on a weak polyelectrolyte brush. Our simulations show a profound influence of even small concentrations of divalent salt on the titration behavior of the brush, which is shown to be a combined effect of electrostatic interactions and the Donnan effect. Furthermore, we examine the partitioning of mono- and divalent counterions into the brush. We demonstrate the preferred uptake of divalent ions by the brush, which is further enhanced by electrostatic correlation effects. Finally, our simulations reveal a hitherto unobserved two-stage swelling of the brush as a function of the pH in the presence of divalent salt. This phenomenon arises as a consequence of charge regulation and ion partitioning.

中文翻译：

弱聚电解质刷与二价抗衡离子的意外两阶段膨胀

我们使用基于粒子的粗粒度模拟来研究二价抗衡离子对弱聚电解质刷的影响。我们的模拟显示，即使是很小浓度的二价盐也会对刷子的滴定行为产生深远的影响，这被证明是静电相互作用和唐南效应的综合效应。此外，我们检查了单价和二价抗衡离子在刷中的分配。我们证明了刷子对二价离子的优先吸收，静电相关效应进一步增强了二价离子的吸收。最后，我们的模拟揭示了在二价盐存在的情况下，刷子迄今为止未观察到的两阶段膨胀，作为 pH 值的函数。这种现象是电荷调节和离子分配的结果。

更新日期：2024-08-22

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