High-strength and self-healable poly (acrylic acid) /chitosan hydrogel with organic-inorganic hydrogen bonding networks

Bentonite is a natural clay mineral with high cationic exchange properties and plays an important role in organic-inorganic composite hydrogels. We report an organic-inorganic cross-linked self-healing hydrogel with excellent mechanical properties by introducing acrylic acid-modified bentonite (AABT) into its cross-link network. AABT with unsaturated double bonds was co-polymerized with AA to construct the hybrid cross-link network of the hydrogel. Then, the carboxyl groups in the PAA chain reacted with CS to form a physically cross-linked network with a hydrogen bond structure. As confirmed by FTIR, XRD, XPS and SEM, the AABT participated in the formation of the hydrogel network, and the hydrogen bonds between PAA and CS chains were formed. Our AABT-PAA/CS hydrogels possessed tensile strength, compressive modulus and elongation at break as high as 0.96 MPa, 4.5 MPa and 1331%, respectively. Besides, our hydrogels also exhibited excellent self-healing properties, with recovered rate stress and strain of ~76.6% and ~77.7% after 4 h, respectively.