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

Abstract

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 model soft particulate gels at different volume fractions using coarse-grained molecular dynamics simulations. We first study a particulate network with local bending stiffness and then we combine it with a second component that can provide additional cross-linking to obtain two-component networks. Through the sequence of physical processes (SPP) framework, we define time-resolved dynamic moduli, and by tracking the changes in these moduli through the period, we can 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.

Thermoresponsive oil-continuous gels based on double-interpenetrating colloidal-particle networks

“…This journal is © The Royal Society of Chemistry 2024 networks during yielding in analogy to what is observed for gel networks made of ''rough'' and ''less mobile'' single colloidal aggregates. 16,24,51 Taking together our experimental findings, we propose that double gels tend to be more resilient and harder to yield, as interpenetration of gel networks lead to densely packed and more interconnected structures. Such structures remain more elastic as gel clusters are much less able to align under shear flow and experience large non-affine deformations (Fig.…”

“…Unfortunately, only a limited number of experimental and theoretical studies have been conducted to demonstrate the feasibility of multicomponent gels and investigate in detail their mechanics. 21,23,24 Particularly, in binary mixtures of colloidal particles with selective interparticle interactions (e.g., in DNA-coated colloids, microgels), both experiments and theory highlight a rich plethora of structures (e.g., double gel networks, core-shell networks) and rheological properties (e.g., softening, toughening, stiffening). Although structurally different, the reported rheology appears to share essential features with the well-explored interpenetrating polymer networks utilized for the creation of tough hydrogels for diverse technological uses.…”

“…Unfortunately, only a limited number of experimental and theoretical studies have been conducted to demonstrate the feasibility of multicomponent gels and investigate in detail their mechanics. 21,23,24 Particularly, in binary mixtures of colloidal particles with selective interparticle interactions ( e.g. , in DNA-coated colloids, microgels), both experiments and theory highlight a rich plethora of structures ( e.g.…”

Competition among physical, chemical, and hybrid gelation mechanisms in biopolymers

“…Our LB curves are similar to recent simulation results for colloidal gels. 43 For matured chemical gels at g 0 = 110%, we observe a small deviation from the linear viscoelastic behavior. In the s/s 0 vs.…”

A comparison between the FENE-P and sPTT constitutive models in large-amplitude oscillatory shear

“…Similarly, for the viscous modulus, increasing values of represent intra-cycle shear-thickening, whereas decreasing values of represent intra-cycle shear-thinning. Negative instantaneous values of can be thought of as representing elastic recoil, and negative instantaneous values of can be thought of as representing viscous backflow (Rogers 2017; Choi, Nettesheim & Rogers 2019; Donley, Bantawa & Gado 2022). In this subsection, we perform the SPP analysis for the sPTT (FENE-P) responses for a fixed with .…”