A Constitutive Model for Mechanical Behaviors of Novel Double Network Hydrogels with Mechanophores

Abstract

Double network hydrogels (DN hydrogels) with high stretchability and toughness have attracted broad research interest. Recently, a kind of novel tough DN hydrogels was designed by means of the reactive strand extension strategy, which introduced mechanophores into the first network. When the strands of the first network reach their nominal stretching limit, the mechanophores allow the strands to survive through force-coupled reactions instead of fracture. As a consequence, the novel hydrogels can achieve a better mechanical performance compared with the conventional DN hydrogels. In this work, we aim to develop a constitutive model for the novel DN hydrogels. The model is based on the worm-like single-chain model by introducing bond deformation. The network alteration theory is used to account for the damage behaviors. The theoretical framework is capable of clarifying the difference in mechanical behaviors between conventional and novel DN hydrogels, which demonstrates the importance of bond deformation on the mechanical behaviors of DN hydrogels.