The preparation of double network hydrogel with high mechanical properties by photopolymerization under the green LED irradiation and enhancement of wet adhesion by tannic acid

Double network hydrogel with excellent mechanical properties is a polymer material composed of interpenetrating polymer network structure. In this study, poly(acrylamide-co-acrylic acid)/sodium alginate (P(AAM-co-AAC)/SA) hydrogels were rapidly prepared by photopolymerization under green LED irradiation. Subsequently, poly(acrylamide-co-acrylic acid)/sodium alginate/tannic acid (P(AAM-co-AAC)/SA/TA) hydrogels were prepared by immersion method. The morphology, mechanical properties, the wet adhension ability and swelling behaviour morphology of P(AAM-co-AAC)/SA/TA hydrogels were studied in detail. The double network hydrogel has excellent mechanical properties, with the elongation at break and tensile strength reaching 862% and 0.77 MPa respectively. The hydrogel with tannic acid showed excellent adhesion, wet adhesion and anti-swelling capability. Our research provides a more efficient and environmentally friendly preparation method for hydrogels used in wet environment.