Nanocomposite Hydrogels as Soil Additives

Recent advancements in geotechnical engineering involve replacing pore water with chemical or biological-based solutions instead of cement to strengthen soil. One such candidate is a nanocomposite hydrogel which is formed from physical attractions between hydrophilic polymer chains and nanoparticles. They have enhanced properties and can retain higher amounts of water. Here, we use molecular dynamics simulations to study structure formation, dynamics and mechanics of these polymer gels as a function of nanofiller volume fraction under both equilibrium and non-equilibrium conditions.  Nanofillers were modeled as bodies of disk-like shapes, with strong rigid bonds and a non-bending cosine harmonic potential between each sub-particle. Physical crosslinks were simulated by introducing a short-range attraction between the nanofillers and polymer chain monomers. We model gels both with a single polymer, as well as a binary mixture of polymers to study the effects of polymer chain interaction and assembly on structure formation and gelation of these systems. Our results show that assembly between the nanoparticles is an important determinant of the final properties of the gel which is mediated by the types and interactions of the polymer used.