Work

Unexpected Two-Stage Swelling of Weak Polyelectrolyte Brushes with Divalent Counterions

Year: 2024

Type: article

Abstract: 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.

Source: ACS Macro Letters

DOI: 10.1021/acsmacrolett.4c00421

Authors: David Beyer, Christian Holm

Institution: University of Stuttgart

Language: English

Topic: Electrostatics and Colloid Interactions

Subfield: Physical and Theoretical Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funder: Deutsche Forschungsgemeinschaft

Awards: G1486546336, Adaptive Polymergele mit kontrollierter Netzwerkstruktur, Ionenverteilung in geladenen Hydrogelen im Gleichgewicht und unter dem Einfluss externer Stimuli, FOR 2811: Adaptive Polymergele mit kontrollierter Netzwerkstruktur, Simulationen von Gleichgewichtsreaktionen in Polymersystemen Methodenentwicklung und Anwendungen