Scaling of Shear Rheology of Concentrated Charged Colloidal Suspensions across Glass Transition.

Electrostatic interparticle interactions are a key component in controlling and designing the rheological characteristics of concentrated charged colloidal suspensions. Herein, we investigate electroviscous effects on shear rheology using highly charged silica particles. By fixing the volume fraction but varying the salinity, the system undergoes a glass transition as evidenced by the evolution of the yield stress and zero-shear viscosity. We show that the steady shear viscosities obey a critical scaling relation that scales the flow curves into a supercritical branch and a subcritical branch with glass transition salinity serving as the bifurcation point; we also demonstrate an isoviscosity scaling that collapses all isoviscosity lines into a single master curve that exhibits no singularity. On the basis of each scaling relation, in conjunction with common modeling equations, the quantitative relationships between the shear viscosity, stress, and salinity are established. This study demonstrates a new framework to model the steady shear rheology of concentrated charged colloids.