Interplay between gelation and glass formation in silica nanoparticle colloids

Silica-based colloids, such as Ludox, are complex fluids with diverse applications in industry, geophysics, and biomedicine. These materials exhibit rich rheological behavior in response to external stimuli, including heating, drying, and shear. However, how such stimuli modulate the particle architecture underlying the material’s mechanical response remains poorly understood. Here, using numerical simulations, we show how drying-induced variations in effective pair potential and particle concentration drive a continuous transition from a percolated gel to a dynamically arrested glass. Comparison of numerical results with experimental rheological data demonstrates that these two phase states correspond to distinct mechanical behaviors. We further propose a global scaling law for the diffusion coefficient that captures the percolation threshold as a function of electrostatic repulsion and thermal fluctuations. Overall, our findings provide predictive insights that may apply to a broad class of colloidal dispersions governed by short-range attractive, long-range repulsive (SARL) interactions.