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Alexander Alexeev1 Svetoslav Nikolov1

1, Georgia Institute of Technology, Atlanta, Georgia, United States

Using dissipative particle dynamics (DPD), we develop a mesoscale model of microgel particle and use it to probe the underlying mechanics and kinetics of microgels throughout the volume-phase transition. By applying non-linear fitting to Flory-Rehner model, we establish a direct connection between our simulations and experiments. We find good agreement of microgel swelling kinetics with Tanaka’s theory. The simulations reveal that gel swelling proceeds significantly slower than gel deswelling. Deswelling is characterized by high network inhomogeneity due to polymer chain bundling, which accelerates the network collapse. We probe the effect of crosslink density on the volume transition and show that its decrease leads to a sharper volume phase transition near the critical point. Finally, we examine the bulk modulus of compressed microgel suspensions at different packing fractions and solvent conditions. We evaluate the degree of particle-particle penetration to establish its relation to the micromechanics of compressed microgel suspensions.

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