Robust Hydrogel with Significant Swelling Resistance via the Synergy of Hydrogen Bond Regulation and Ionic Cross-linking

The development of high-performance hydrogels has received much attention, but the simple and cost-effective preparation of hydrogels with high mechanical strength and excellent swelling resistance remains a challenge. In this study, a facile and green strategy was proposed to construct a polyvinyl alcohol/chitosan-based (PVA/CS-based) hydrogel with high mechanical strength and superior swelling resistance. By introducing tannic acid (TA), a natural polyphenol, and forming hydrogen bonding cross-linking with the polymer chains through solvent regulation, as well as by ionic cross-linking and salting-out effects further induced through sodium citrate solution immersion, a strong and homogeneous multiple physical cross-linking network was formed, which endowed the resulting hydrogel with excellent mechanical and swelling resistance performance. For the hydrogel with PVA, CS, and TA in the mass ratio of 5:1:5, the tensile strength was up to 8.22 MPa, and the tensile strength retention was up to 96% of the original value after swelling equilibrium. In addition, our hydrogel can be attached in situ to various substrates and enabled wet adhesion. The easy scale-up and energy-saving features made our method highly promising for the preparation of high-performance hydrogels for many advanced applications.

Automated summary

A simple and environmentally-friendly strategy to prepare a polyvinyl alcohol/chitosan-based (PVA/CS-based) hydrogel with high mechanical strength and excellent swelling resistance was proposed. The hydrogel was formed by introducing tannic acid (TA) as well as through hydrogen bonding crosslinking and ionic crosslinking induced by sodium citrate solution immersion. The resulting hydrogel exhibited superior mechanical strength and swelling resistance performance.