ACS Appl Mater Interfaces. 2019 Sep 25;11(38):35343-35353. doi: 10.1021/acsami.9b12935. Epub 2019 Sep 11.
The double network concept, based on the fracture of sacrificial bonds, has been revolutionary toward the creation of robust soft materials. Based on the essence of double network hydrogels, macroscale, three-dimensional printed rigid sacrificial networks are embedded within silicone rubber stretchable matrices. Preferential fracture of the sacrificial network results in a ∼60 time increase in stiffness and a ∼50% increase in the work of extension compared with the neat matrix. Maximizing yield strength while maintaining multistep internal fracture occurs when the strength of the sacrificial network approaches the strength of the matrix. Upon determining the optimal sacrificial network strength, the sacrificial bond section density can be increased to maximize energy dissipation and toughening efficiencies up to ∼70% of the maximum theoretical toughness are achieved. High toughness and dissipation are achieved because topological interlocking enables significant force transmission to the sacrificial network at smaller length scales than interfacial adhesion, allowing much higher sacrificial bond density. This method is general and can be used with a variety of materials systems, without requiring strong interfacial adhesion, contrasting traditional composite systems. Demonstrating that the double network concept can be used at length scales far beyond the molecular scale will have important implications toward the development of future structural materials.
基于牺牲键断裂的双网络概念，对于创造强韧的软材料具有革命性意义。基于双网络水凝胶的本质，宏观的、三维打印的刚性牺牲网络被嵌入到硅橡胶可拉伸基质中。牺牲网络的优先断裂导致其刚度提高约 60 倍，与纯基质相比，延伸功提高约 50%。当牺牲网络的强度接近基质的强度时，会发生最大化屈服强度同时保持多步内部断裂的情况。在确定最佳牺牲网络强度后，可以增加牺牲键截面密度，以最大化能量耗散和增韧效率，最高可达最大理论韧性的 70%。高韧性和高耗散性是因为拓扑互锁可以在比界面附着力小得多的长度尺度上向牺牲网络传递显著的力，从而允许更高的牺牲键密度。这种方法具有通用性，可以与各种材料系统一起使用，而不需要强的界面附着力，与传统的复合材料系统形成对比。证明双网络概念可以在远远超出分子尺度的长度尺度上使用，这将对未来结构材料的发展产生重要影响。
