Mechanoresponsive resonance differences in double-network hydrogels towards multipartite dynamics

Unlike single-network hydrogel whose thermodynamic equilibrium of all phases is governed by one single rule, double-network (DN) hydrogel is incorporated of two coexisting phases, which are separated from each other due to the differences in their mechanoresponsive responses. However, the resonance differences and multipartite dynamics of coexisting phases in these DN hydrogels have not been fully understood. This paper reports a new methodology to use a rheological model in combination of Arrhenius principle and Kirkwood approximation, to characterize the differences in mechanoresponsive resonances and viscoelastic behaviors of coexisting phases in the DN hydrogel. Their multipartite dynamics has been identified to originate from mechanical stretching, mechanochemical coupling and chemical kinetics of the ductile network, original brittle network and self-healed brittle network, respectively. Furthermore, molecular dynamics simulation and finite-element analysis have been conducted to verify the proposed model and explore the toughening mechanism, which is determined not only by the mechanochemical coupling, but also by the self-healing kinetics. Finally, effectiveness of proposed model has been well verified using the experimental results of DN hydrogels reported in literature.