Recent advancements in geotechnical engineering involves replacing pore water with chemical or biological solutions instead of cement to strengthen the soil. One such candidate is a nanocomposite hydrogel. These hydrogels are formed from the physical attractions between hydrophilic polymer chains and nanoparticles. They have enhanced properties and can retain higher amounts of water. Despite the large number of experimental studies on this topic, little is known about the mechanism of formation and structure of these gels.<br/>Here, we use molecular dynamics simulations to study structure formation in physically associating nanocomposite hydrogels. Nanofillers were modeled as bodies of disk-like shapes, with each sub-particle connected to each other with strong rigid bonds and a non-bending cosine harmonic potential. Physical crosslinks were simulated by introducing a short-range attraction between the nanofillers and polymer chain monomers.<br/>The structure, dynamics and mechanics of these polymer gels were studied as a function of nanofiller volume fraction under both equilibrium and non-equilibrium conditions. 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. This assembly is mediated by the types and interactions of the polymer used.

Nanocomposite hydrogels as soil additives

ACS Spring 2022

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