Journal Article

FZJ-2019-06370

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Modeling deswelling, thermodynamics, structure, and dynamics in ionic microgel suspensions

Brito, M. E.FZJ* ; Denton, A. R. ; Nägele, G. (Corresponding author)FZJ*

2019
American Institute of Physics Melville, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/23705  doi:10.1063/1.5129575

Abstract: Ionic microgel particles in a good solvent swell to an equilibrium size determined by a balance of electrostatic and elastic forces. Whencrowded, ionic microgels deswell owing to a redistribution of microions inside and outside the particles. The concentration-dependentdeswelling affects the interactions between the microgels, and, consequently, the suspension properties. We present a comprehensive theoreticalstudy of crowding effects on thermodynamic, structural, and dynamic properties of weakly cross-linked ionic microgels in a good solvent.The microgels are modeled as microion- and solvent-permeable colloidal spheres with fixed charge uniformly distributed over the polymergel backbone, whose elastic and solvent-interaction free energies are described using the Flory-Rehner theory. Two mean-field methods forcalculating the crowding-dependent microgel radius are investigated and combined with calculations of the net microgel charge characterizingthe electrostatic part of an effective microgel pair potential, with charge renormalization accounted for. Using this effective pair potential,thermodynamic and static suspension properties are calculated including the osmotic pressure and microgel pair distribution function. Thelatter is used in our calculations of dynamic suspension properties, where we account for hydrodynamic interactions. Results for diffusionand rheological properties are presented over ranges of microgel concentration and charge. We show that deswelling mildly enhances selfdiffusionand collective diffusion and the osmotic pressure, lowers the suspension viscosity, and significantly shifts the suspension crystallizationpoint to higher concentrations. This paper presents a bottom-up approach to efficiently computing suspension properties of crowdedionic microgels using single-particle characteristics.

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Contributing Institute(s):

1. Weiche Materie (ICS-3)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)

Appears in the scientific report 2019

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; National-Konsortium ; Nationallizenz ; PubMed Central ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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