Elastomers that can sustain large reversible strain are essential components for stretchable electronics. The stretchability and mechanical robustness of unfilled elastomers can be enhanced by introducing easier-to-break cross-links, e.g. through the multi-network structure, which also causes stress–strain hysteresis indicating strain-induced damage. However, it remains unclear whether cross-link breakage follows a predictable pattern that can be used to understand the damage evolution with strain. Using coarse-grained molecular dynamics and topology analyses of the polymer network, we find that bond-breaking events are controlled by the evolution of the global shortest path length between well-separated cross-links, which is both anisotropic and hysteretic with strain. These findings establish an explicit connection between the molecular structure and the macroscopic mechanical behavior of elastomers, thereby providing guidelines for designing mechanically robust soft materials.

可以承受较大可逆应变的弹性体是可拉伸电子产品的基本组件。未填充弹性体的可拉伸性和机械强度可以通过引入易于断裂的交联来增强，例如通过多网络结构，这也会引起应力应变滞后现象，表明应变引起的破坏。然而，目前尚不清楚交联断裂是否遵循可预测的模式，该模式可用于理解应变引起的损伤演化。使用粗粒度的分子动力学和聚合物网络的拓扑分析，我们发现键断裂事件是由完全分开的交联点之间的全局最短路径长度的演变控制的，该长度最短既各向异性又具有应变滞后性。