Shear-Induced Behavior of Nanocomposite Hydrogels Using Molecular Dynamics Simulations

Nanocomposite hydrogels (NCHs) overcome the mechanical limitations of conventional hydrogels by offering superior elasticity, toughness, and water retention – properties that enable geotechnical applications such as soil stabilization and frost resistance. In these contexts, understanding their response to shear is critical, as it governs flow behavior, energy dissipation, and network stability under deformations. However, probing shear-induced structural changes at the molecular scale remains experimentally challenging due to high water content and complex polymer-nanofiller-solvent interactions.

Here, we employ molecular dynamics simulations, with explicit solvent particles, to investigate the shear response of NCHs containing platelet-shaped nanofillers, under both charged and uncharged conditions. The nanofillers act as multifunctional crosslinking junctions that adsorp polymer chains, forming a percolating 3D network that enhances mechanical integrity. Our simulations reveal that increasing nanofiller concentration increases shear viscosity, leading to a gelation transition at 2.18% nanofillers. Upon application of shear, the NCHs display pronounced shear-thinning behavior, driven by nanofiller and polymer chain alignment along the flow direction. We further examine rheology, network connectivity, and structural orientation across varying shear rates, thereby providing molecular-level insight into the structure-property relationships of NCHs.