Tough and Self-Healing Chitosan/Poly(acrylamide-co-acrylic acid) Double Network Hydrogels

Chitosan/poly(acrylamide-co-acrylic acid) double network hydrogels based on non-covalent bond and winding between molecular chains were synthesized by copolymerization reaction in the presence of Fe3+. The formation mechanism of chitosan/poly(acrylamide-co-acrylic acid) double network hydrogels was analyzed using UV–Vis spectra and FTIR, revealing that Fe3+ could form the electrostatic interaction with –COO– group in poly(acrylamide-co-acrylic acid) chains, and the –COOH form also the hydrogen bond also with –CONH2 in poly(acrylamide-co-acrylic acid) chains or –NH2 in chitosan chains. Mechanical properties of the prepared double network hydrogels were investigated by rheological and mechanical measurements. These results indicated that the chitosan/poly(acrylamide-co-acrylic acid) double network hydrogels present good recovery ability. The tensile strength and elongation at break of the synthesized hydrogel could reach 141.9 kPa and 18.2 mm/mm, respectively, their compressive strength could reach 1.76 MPa at strain of 85%. In addition, the synthesized hydrogels can maintain good self-healing capacity owing to the dynamically reversible bonds (ionic bond and hydrogel bonding). This work provides a facile method for the synthesis of hydrogels with toughness and self-healing capacity. The synthesized chitosan/poly(acrylamide-co-acrylic acid) double network hydrogels would have a great potential applications in a diverse range.