Strain-Induced Crystallization in Tetra-Branched Poly(ethylene glycol) Hydrogels with a Common Network Structure

Strain-induced crystallization (SIC) in hydrogels is a recently discovered toughening mechanism. This mechanism necessitates highly orientated polymer chains during stretching; thus, SIC is thought to be limited to specially designed networks, such as slidable cross-link networks or tribranched networks. In this study, we report the occurrence of SIC in a model hydrogel network prepared using tetra-branched polymers, which can be classified as a network with a simple and general structure. We propose that the polymer concentration and molecular weight between the branch points are the key factors governing SIC.