  Ionic microgel particles in a good solvent swell to an equilibrium size
determined by a balance of electrostatic and elastic forces. When crowded,
ionic microgels deswell owing to a redistribution of microions inside and
outside the particles. The concentration-dependent deswelling affects the
interactions between the microgels, and consequently the suspension properties.
We present a comprehensive theoretical study 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 polymer gel backbone, whose elastic and solvent-interaction free
energies are described using Flory-Rehner theory. Two mean-field methods for
calculating the crowding-dependent microgel radius are investigated, and
combined with calculations of the net microgel charge characterizing the
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. The latter is used in
our calculations of dynamic suspension properties, where we account for
hydrodynamic interactions. Results for diffusion and rheological properties are
presented over ranges of microgel concentration and charge. We show that
deswelling mildly enhances self- and collective diffusion and the osmotic
pressure, lowers the suspension viscosity, and significantly shifts the
suspension crystallization point to higher concentrations. The paper presents a
bottom-up approach to efficiently computing suspension properties of crowded
ionic microgels using single-particle characteristics.
