Résumé
Network-forming materials are ubiquitous and appear in industrial products such as tires, food andcosmetics as well as composing the cytoskeleton within the cells of living organisms. They arelightweight and display desirable properties such as optical transparency and reversible deformability up to large strains. However, the microscopic mechanisms protecting a network againstmacroscopic fracture and the processes that control crack growth are still poorly under-stood. Adeeper understanding is needed to fully exploit the potential of polymer networks in advanced andnovel material design. In recent years a general phenomenon has emerged where materialscomposed of an interpenetrated stiff filler network and a soft matrix network display toughness fargreater than either constituent [1,2]. Herein we adapt photon correlation imaging [3] (PCI) to revealthe microscopic rearrangements within poly(ethyl acrylate), PEA, networks [4] during deformationby extension and fracture (see figure 1). We examine how such rear-rangements differ in a simplePEA network and in double network composed of two interpene-trated PEA networks, one stretchedand stiffer with respect to the other. We find that rearrange-ments in the double networks occur overlarger distances strain windows thereby serving to re-duce stress at a crack tip and hinder itspropagation.References [1] J. P. Gong, Y. Katsuyama, T. Kurokawa, and Y. Osada Adv. Mater., 2003 15, 1155.[2] E. Ducrot, Y. Chen, M. Bulters, R. P. Sijbesma, and C. Creton Science, 2014 344, 186. [3] A.Duri, D. A. Sessoms, V. Trappe, and L. Cipelletti Phys. Rev. Lett., 2009 102(8), 085702. [4] P.Millereau, E. Ducrot, J. M. Cloug