This title appears in the Scientific Report : 2019 

Modeling deswelling, thermodynamics, structure, and dynamics in ionic microgel suspensions
Brito, Mariano E.
Denton, Alan R. / Nägele, Gerhard (Corresponding author)
Weiche Materie ; ICS-3
The journal of chemical physics, 151 (2019) 22, S. 224901 -
Melville, NY American Institute of Physics 2019
10.1063/1.5129575
Journal Article
Functional Macromolecules and Complexes
Published on 2019-12-09. Available in OpenAccess from 2020-12-09.
Published on 2019-12-09. Available in OpenAccess from 2020-12-09.
Please use the identifier: http://hdl.handle.net/2128/23705 in citations.
Please use the identifier: http://dx.doi.org/10.1063/1.5129575 in citations.
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.