  Ionic microgel particles are intriguing systems in which the properties of
thermo-responsive polymeric colloids are enriched by the presence of charged
groups. In order to rationalize their properties and predict the behaviour of
microgel suspensions, it is necessary to develop a coarse-graining strategy
that starts from the accurate modelling of single particles. Here, we provide a
numerical advancement of a recently-introduced model for charged co-polymerized
microgels by improving the treatment of ionic groups in the polymer network. We
investigate the thermoresponsive properties of the particles, in particular
their swelling behaviour and structure, finding that, when charged groups are
considered to be hydrophilic at all temperatures, highly charged microgels do
not achieve a fully collapsed state, in favorable comparison to experiments. In
addition, we explicitly include the solvent in the description and put forward
a mapping between the solvophobic potential in the absence of the solvent and
the monomer-solvent interactions in its presence, which is found to work very
accurately for any charge fraction of the microgel. Our work paves the way for
comparing single-particle properties and swelling behaviour of ionic microgels
to experiments and to tackle the study of these charged soft particles at a
liquid-liquid interface.
