Water Non-swellable And High-strength Polyacrylic Acid-based Adhesive Hydrogels

The reported polyacrylic acid-based hydrogels exhibited high water-swellable properties,which resulted in weak bulk strength and low adhesion strength,thus limiting their applications in wet conditions as adhesives.In this work,we proposed a simple method for preparing a water non-swellable and high-strength polyacrylic acid-based adhesive hydrogel.A chemical and hydrogen bonded crosslinked hydrogel was prepared by thermo-initiated radical polymerization of acrylic acid,2-vinyl-4,6-diamino-1,3,5-triazine(VDT)and poly(ethylene glycol)diacrylate(PEGDA).Incorporation of the crosslinking agent PEGDA improved the toughness of the hydrogels,while the mechanical properties and swelling stability of the hydrogel were enhanced due to hydrophobic hydrogen bonding interactions of VDT.The synergistic effects of PEGDA and VDT could strengthen the mechanical properties of the hydrogels whose maximum tensile strength and compression strength could reach1.24 MPa and 5.66 MPa.Without any external stimulus,the hydrogel could adhere to different materials.The maximum adhesive strengths of the hydrogels to the pigskin and iron could reach up to 105 k Pa and 99 k Pa,respectively.The high adhesion strength to iron could be maintained for at least 24 h under water.Interestingly,this hydrogel could rapidly bond and repair the perforated pigs’ bladders in vitro,preventing the leakage of simulated urine within 72 h.This hydrogel is promising to be developed as a first-aid bandage for emergency self-rescue.