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

Abstract

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.

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“…Subsequently, the resultant mixture underwent thorough mixing and was subjected to a drying process using a rotary evaporator operating under conditions of 40 mbar, 45 � C and 190 revolutions per minute. Even though the surface-charge distribution of the silica particles may change after this treatment, the particle surface retains its electrostatic negativity, with repulsive interactions between the silica particles (Wu et al, 2022). Therefore, the interaction can still be modeled as a Yukawa potential after resuspension.…”