Time-resolved microstructural changes in large amplitude oscillatory shear of model single and double component soft gels

Soft particulate gels can reversibly yield when sufficient deformation is applied, and the characteristics of this transition can be enhanced or limited by designing hybrid hydrogel composites. While the microscopic dynamics and macroscopic rheology of these systems have been studied separately in detail, the development of direct connections between the two has been difficult, particularly with regard to the nonlinear rheology. To bridge this gap, we perform a series of large amplitude oscillatory shear (LAOS) numerical measurements on a series of model soft particulate gels using coarse-grained molecular dynamics simulations. We study both a particulate network with local bending stiffness and a two-component network with a second component that provides additional cross-linking. Through the sequence of physical processes (SPP) framework, we define and track time-resolved dynamic moduli which allow us to distinguish transitions in the material behavior as a function of time. This approach helps us establish the microscopic origin of the nonlinear rheology by connecting the changes in dynamic moduli to the corresponding microstructural changes during the deformation including the nonaffine displacement of particles, and the breakage, formation, and orientation of bonds.