Mechanical and Rheological Behavior of Hybrid Cross-Linked Polyacrylamide/Cationic Micelle Hydrogels

In this work, a hybrid cross-linked polyacrylamide (PAM)/cationic micelle hydrogel is fabricated by introducing the cationic micelles into the chemically cross-linked PAM network. The cationic micelles act as the physical cross-linking points through the strong electrostatic interaction with anionic initiator potassium persulfate. Thereafter, in situ free radical polymerization is initiated thermally from the cationic micelle surface to form the hybrid cross-linked network. The synergistic effect between chemical and physical cross-link endows the hydrogel with excellent mechanical and recoverable properties. The resulting hydrogel exhibits tensile stress of 481 kPa and fracture toughness of 1.65 MJ m(-3). It is found that the chemical cross-linking can inhibit the hysteresis of the hybrid hydrogel, exhibiting good elasticity in the tensile loading-unloading test. Moreover, dynamic rheological measurements show that the hybrid hydrogels possess fewer defects of network and exhibit excellent self-recovery behavior. Thus, this investigation provides a different view for the design of new high elastic and tough hydrogels containing hybrid physical and chemical cross-linking networks.