A molecular understanding of the fracture process of model end-linked polymer networks

The fracture of end-linked polymer networks and gels significantly impacts the performance of these versatile and widely used materials, making a molecular-level understanding of the fracture process essential for designing new materials. The Lake-Thomas theory provides a foundation for quantifying energy dissipation due to chain scission. Recent extensions of the Lake-Thomas theory have incorporated the effect of topological defects, such as loop defects, and have improved the accuracy of fracture energy predictions. However, the mechanism of how energy is stored and dissipated within the complex structure of polymer networks remains insufficiently explored, and molecular-level details are needed to complete the story. In this talk, I will describe how we use coarse-grained molecular dynamics simulations and network analysis to offer a molecular view of the energy dissipated from chain scission in polymer networks. In addition to the energy from the broken strand, we also trace the amount of energy stored and released from the surrounding tree-like networks during the chain scission process. Network analysis techniques are used to further understand how the inhomogeneous nature of network structure affects energy and stress transmission. Our findings refine the description of the processes at play during the failure of polymer networks.