Fracture behaviors of double network elastomers with dynamic non-covalent linkages: A molecular dynamics study

Hybrid double network (HDN) elastomers, containing the physical interaction (PI) network formed by non-covalent interaction and the chemically cross-linked (C-CL) network, attract enormous interest due to the excellent toughness. Herein, the fracture process of HDN elastomers is elucidated via coarse-grained molecular dynamics simulation methods, which is essential to improve the toughness. The evolution of microstructures, including voids, and clusters serving as cross-linked points in the PI network, is analyzed to understand the fracture behavior. Secondly, the influence of PI strength on toughness is investigated. As the PI strength increases, the dissociation of clusters dissipates more energy. In addition, more bond scissions in the C-CL network also contribute to the promotion of toughness. In summary, this work provides the molecular perspective of the fracture and contributes to preparing HDN elastomers with high toughness. • The fracture behavior of hybrid double network elastomers is revealed in detail. • The evolution of the clusters, free volumes, and voids is characterized. • The toughness is originated from resistances of clusters to dissociation and bonds to scission. • As the physical interaction strength rises, both resistances are improved, leading to the high toughness.