Prediction of the Interaction Potential of Microgel Particles from Rheometric Data. Comparison with Different Models

This work is concerned with the determination of the effective particle−particle interaction in colloidal suspensions from rheology. In particular, a concentrated microgel suspension is considered, in which particles interact through a repulsive polymer−polymer potential. The rheological modeling of this suspension was carried out by the authors in a recent work. Here, the interaction potential provided by that model is compared with the ones resulting from different models found in the literature. In this sense, a series of approaches relating the pair potential to rheological data such as dynamic modulus, viscosity, and yield stress is examined. Then the results of applying these models to experimental data are discussed, showing the advantages and limitations of each approach for the particular case of concentrated microgel suspensions. de Gennes' theoretical pair potential for polymer-covered particles is also included for comparison. The proposed viscosity model appears rather general and it is expected to have success in determining the effective potential in colloidal systems with different particle−particle force laws.