Softness-Driven Packing and Rheology of PEG Nanogel Assemblies

Soft hydrogel particles are useful building blocks for injectable and adaptive soft materials, but their collective behavior is governed by more than particle size alone. When concentrated, soft nanogels can deform, deswell, and reorganize, producing packing structures that differ fundamentally from those of hard colloids. These particle-level responses can strongly influence interparticle voids, macroscopic rheology, and transport-relevant pathways within the assembled material. In this work, we use PEG-based nanogels as a model soft colloidal system to investigate how particle softness and formulation conditions affect collective structure formation. PEG nanogels are prepared through emulsion-templated gelation, enabling control over particle properties through the dispersed-phase composition and gelation conditions. We examine the relationship between nanogel design, concentrated assembly behavior, and bulk rheological response. By connecting single-particle softness to collective material properties, this study aims to provide design principles for PEG nanogel assemblies and broader insight into the structure–property relationship of soft colloidal hydrogels.