Highly Mechanical and Fatigue‐Resistant Double Network Hydrogels by Dual Physically Hydrophobic Association and Ionic Crosslinking

Abstract

Abstract Double network (DN) hydrogels with high strength and toughness are considered as promising soft materials. Herein, a dual physically cross‐linked hydrophobic association polyacrylamide (HPAAm)/alginate‐Ca 2+ DN hydrogel is reported, consisting of a HPAAm network and a Ca 2+ cross‐linked alginate network. The HPAAm/alginate‐Ca 2+ DN hydrogel exhibits excellent mechanical properties with the fracture stress of 1.16 MPa (3.0 and 1.7 times higher than that of HPAAm hydrogel and HPAAm/alginate hydrogel, respectively), fracture strain of 2604%, elastic modulus of 71.79 kPa, and toughness of 14.20 MJ m −3 . HPAAm/alginate‐Ca 2+ DN hydrogels also demonstrate self‐recovery, notch‐insensitivity, and fatigue resistance properties without any external stimuli at room temperature through reversible physical bonds consisting of hydrophobic association and ionic crosslinking. As a result, the dual physical crosslinking would offer an avenue to design DN hydrogels with desirable properties for broadening current applications of soft materials.