Laboratoire SIMM, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 75231 Cédex 05 Paris, France.
Proc Natl Acad Sci U S A. 2022 Mar 29;119(13):e2116127119. doi: 10.1073/pnas.2116127119. Epub 2022 Mar 24.
SignificanceSoft materials can be toughened by creating dissipative mechanisms in stretchy matrixes. Yet using them over a wide range of temperatures requires dissipative mechanisms independent of stretch rate or temperature. We show that sacrificial covalent bonds in multiple network elastomers are most useful in toughening elastomers at high temperature and act synergistically with viscoelasticity at lower temperature. We do not attribute this toughening mechanism only to the scission of bonds during crack propagation but propose that the highly stretched network diluted in a stretchy matrix acts by simultaneously stiffening the elastomer and delaying the localization of bond scission and the propagation of a crack. Such a toughening mechanism has never been proposed for elastomers and should guide network design.
软物质可以通过在可拉伸基质中创建耗散机制来增韧。然而，要在广泛的温度范围内使用它们，则需要与拉伸率或温度无关的耗散机制。我们表明，在多种网络弹性体中的牺牲共价键在高温下增强弹性体的韧性方面最为有用，并且在低温下与粘弹性协同作用。我们不仅将这种增韧机制归因于裂纹扩展过程中键的断裂，而且还提出在拉伸基质中高度拉伸的网络通过同时使弹性体变硬并延迟键断裂的局部化和裂纹的扩展，从而起到增强韧性的作用。这种增韧机制从未在弹性体中提出过，应该指导网络设计。
