Scaling Behavior of Fracture Properties of Tough Adhesive Hydrogels

Tough adhesive hydrogels find broad applications in engineering and medicine. Such hydrogels feature high resistance against both cohesion and adhesion failure. The superior fracture properties may, however, deteriorate when the hydrogels swell upon exposure of water. The underlying correlation between the polymer fraction and fracture properties of tough adhesive hydrogels remains largely unexplored. Here, we study how the cohesion and adhesion energies of a tough adhesive hydrogel evolve with the swelling process. The results show a similar scaling law (ϕ) of the two quantities as a function of the polymer fraction (ϕ). Our scaling analysis and computational study reveal that it stems from the scaling of shear modulus. The study will promote the investigation of scaling of hydrogel fracture and provide development guidelines for next-generation tough adhesive hydrogels.