damage and loss of percolation depending on the failure regime. This work thus provides a framework for the design and optimization of double network materials and underlines the importance of network structure in the toughness of polymer materials.'
author:
- Justin Tauber
- Simone Dussi
- Jasper van der Gucht
bibliography:
- 'ms.bib'
title: Microscopic insights into the failure of elastic double networks
---

Introduction
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Polymer networks, such as rubbers and gels, can undergo large deformation without losing elasticity. This property makes them ideal for numerous applications, for example in the biomedical field or in soft robotics. One of the factors that limits their applicability, however, is the brittleness of many polymer networks, which leads to inferior mechanical performance, such as low fracture toughness and strength [@Creton2017]. In recent years, several strategies have been developed to toughen polymer networks by introducing dissipation mechanisms that delay crack propagation. One of the most successful strategies relies on the combination of two different polymer networks into one material, to create a so-called double network. In particular, extremely tough double network hydrogels have been produced by interpenetrating a stiff and weak first network with a soft and extensible second network [@Gong2010; @Nakajima2013; @Gong2003; 