Equilibrium properties of charged microgels: a Poisson-Boltzmann-Flory approach

TL;DR

This paper models the equilibrium properties of ionic microgels using a combined Poisson-Boltzmann and Flory approach, revealing how salinity affects swelling, density, and charge characteristics.

Contribution

It introduces a self-consistent method to analyze ionic microgels, emphasizing the impact of salt concentration on their physical and electrostatic properties.

Findings

Salt concentration significantly reduces microgel size.

Microgel swelling releases internal solvent and ions.

Charge renormalization effects are briefly discussed.

Abstract

The equilibrium properties of ionic microgels are investigated using a combination of the Poisson-Boltzmann and Flory theories. Swelling behavior, density profiles, and effective charges are all calculated in a self-consistent way. Special attention is given to the effects of salinity on these quantities. It is found that the equilibrium microgel size is strongly influenced by the amount of added salt. Increasing the salt concentration leads to a considerable reduction of the microgel volume, which therefore releases its internal material -- solvent molecules and dissociated ions -- into the solution. Finally, the question of charge renormalization of ionic microgels in the context of the cell model is briefly addressed.