Rheology of Magnetic Nanogel Suspensions

Magnetic nanogels (MNGs)─deformable colloidal particles composed of cross-linked polymers with embedded magnetic nanoparticles (MNPs)─facilitate remote manipulation of their rheology and internal structure through biocompatible magnetic fields. This property renders MNGs particularly promising for applications in drug delivery and hyperthermia, although the rheological characteristics of these systems are not yet fully understood. In this research, we create an <i>in silico</i> planar rheometer by combining the solutions of Lattice-Boltzmann-based Navier-Stokes equations with molecular dynamics-tracked MNGs trajectories. Conducting steady shear experiments allows us to measure the viscosity of MNG suspensions by evaluating the effects of uniform external magnetic fields (<i>H⃗</i>) (in terms of strength and direction), concentration, and dipolar coupling interactions among MNPs within the MNGs. The application of <i>H⃗</i> hinders colloid rotation and increases viscosity, while rotating <i>H⃗</i> fields generate shear flow in otherwise stationary MNG suspensions. Differences in the rheological behavior between deformable and rigid colloids are highlighted.