Interplay between gelation and glass formation in silica nanoparticle colloids.

Silica-based colloids, like 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. 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. This evolution corresponds to distinct mechanical behaviors, establishing a robust link between microstructure and rheology. We further propose a scaling law for the diffusion coefficient that identifies the system’s percolation threshold, offering a means to experimentally control the sol-gel transition by tuning electrostatic interactions. Overall, our findings provide predictive insights that may apply to a broad class of colloidal dispersions governed by short-range attractive, long-range repulsive (SALR) interactions.