Colloidal gel morphology and phase behavior differs based on the electrostatic interaction model in concentrated electrolytes

Abstract

Predicting how nanoparticles interact in concentrated electrolytes remains a central challenge in nanoscience, with implications spanning energy storage, catalysis, and soft materials design. While Derjaguin-Landau-Verwey-Overbeek (DLVO) theory provides a widely used framework for modeling colloidal interactions, its electrostatic component relies on electric double-layer (EDL) theories whose validity in ionic liquids and concentrated electrolytes is consistently debated. Experiments have revealed significant deviations from classical screening behavior, including underscreening and oscillatory charge ordering, yet the consequences of these nonclassical effects for collective nanoparticle behavior remain unresolved. Here, we demonstrate that the extended range and oscillatory nature of electrostatic screening in concentrated electrolytes predicts different phase behavior and morphology of colloidal ionogels, yielding distinct thermodynamic signatures, percolation thresholds, and amorphous network structures. Using molecular dynamics simulations with DLVO-type pair interactions parameterized by competing EDL models, we systematically compare the consequences of different screening theories on gel formation and configurations.