A good adhesion and antibacterial double-network composite hydrogel from PVA, sodium alginate and tannic acid by chemical and physical cross-linking for wound dressings

Wound dressings play an important role in the wound healing process. For the shortcomings of traditional wound dressings, hydrogel wound dressing with high strength and high water content is a new ideal wound dressing. In this study, polyvinyl alcohol and sodium alginate were selected as raw materials to form the first layer of network structure by physical cross-linking and chemical cross-linking. Then, the double network structure composite hydrogels were obtained by immersed in tannic acid solution. The microstructure, mechanical properties, water content, swelling ratio, antibacterial properties, adhesion properties and rheology of the hydrogels were subsequently investigated. The obtained double network hydrogels have high mechanical properties due to chemical cross-linking and hydrogen bonding interactions, and the maximum tensile strength can reach 4.06 MPa and the elongation at break is up to 569.12%. The optimized calculations from molecular simulations proved that the strengths of the three different types of hydrogen bonds formed reached 37.70, 54.98 and 60.50 kJ/mol, respectively, also justifying the high mechanical strength of the hydrogels. The hydrogel can form good adhesion on various substrate materials such as wood, plastic, glass and pigskin with maximum adhesion strengths of 200.6, 24.8, 24.4 and 13.1 kPa, respectively. Wood surface has higher adhesion strength due to the presence of large amount of cellulose and hydrogen bonds formed by hydrogel. In conclusion, good adhesion can be formed on the surface of different materials. It was a wound dressing with potential application.