Understanding the Self-healing of Reversible Polymer Networks through Molecular Dynamic Simulation

Hydrogels with reversible crosslinking motifs exhibit extraordinary short healing time and high healing strength. However, the understanding about the self-healing behavior of reversible polymer network is limited. Especially, the key problem about relation between the microscopic evolution of polymer networks and the macroscopic stress-strain behaviors during the self-healing process remains largely elusive. In this work, a molecular dynamics / Monte Carlo hybrid coarse-grained model is developed to investigate the relaxation and self-healing behaviors of polymer networks with reversible crosslinking. We systamatically investigate the shelf-healing process of the polymer network with a fracture. It is found that the polymer chains at the fracture interface can diffusive through the interfacial gap and form new crosslinking bonds, resulting the recovery of polymer network mechanical strength. We found that the healing time is both determined by the dwelltime of the dynmaic bond and relaxation of the polymer chains. Our simulations provide a direct relation between dynamic bond and the self-healing process, which might provide an insight for the design of smart self-healing polymers.