Tough, Swelling-Resistant, Self-Healing, and Adhesive Dual-Cross-Linked Hydrogels Based on Polymer–Tannic Acid Multiple Hydrogen Bonds

Abstract

We demonstrate a facile and universal strategy in the fabrication of dual-cross-linked (DC) single network hydrogels with high toughness, “nonswellability”, rapid self-healing, and versatile adhesiveness based on polymer–tannic acid (TA) multiple hydrogen bonds. Two widely used hydrogels, physically cross-linked poly­(vinyl alcohol) and chemically cross-linked polyacrylamide, have been transformed to TA-based DC hydrogels by dipping the corresponding aerogels into TA solution. The second cross-link via multiple polymer–TA hydrogen bonds effectively suppresses the crack propagation, resulting in both DC gels with high mechanical strength. But these two TA-based DC hydrogels go through different deformation mechanisms during the stretching based on analyzing their stress–strain curves using the Mooney–Rivlin equation. Moreover, these DC hydrogels are swelling-resistant, with strong toughness, good self-recoverability, rapid self-healing, and versatile adhesiveness. This work provides a simple route to fabricate multifunctional DC hydrogels, hopefully promoting their applications as biomedical materials.

Tensile Fatigue of Poly(Vinyl Alcohol) Hydrogels with Bio‐Friendly Toughening Agents

“…Toughness was selected as the key metric for screening additives due to its practical applications in the realm of articular cartilage when considering the ability of a hydrogel to dissipate energy, which is a direct relationship to toughness. [ 71–74 ] The results can be seen in Figure a in which toughness is shown for each additive. With these results in view, the top four performing additives on toughness enhancement alone were agar, xanthan gum, starch, and cotton flock.…”

Effects of the degree of crosslinking and test rate on the tensile properties of a crosslinked polyacrylic pressure‐sensitive adhesive and vulcanized rubber

“…In the case of a uniform crosslinking structure, a straight horizontal line should be obtained . However, in actuality, the plotted line will exhibit a small positive gradient and the data points will deviate from a straight line at both large and small values of 1/ λ . Recently, the Mooney–Rivlin plot technique has been widely applied to substances ranging from hydrogels to inorganic particle‐filled rubber composites .…”

“…However, in actuality, the plotted line will exhibit a small positive gradient and the data points will deviate from a straight line at both large and small values of 1/ λ . Recently, the Mooney–Rivlin plot technique has been widely applied to substances ranging from hydrogels to inorganic particle‐filled rubber composites . The degree of orientation of polymer chains and the Payne effect during tensile processes can both be evaluated by assessing the deviation from the straight line in the large and small 1/ λ regions, respectively.…”

“…Originally, C 1 and C 2 were included simply as convenient coefficients in the Mooney–Rivlin equation . However, the chemical and physical meanings of these coefficients have been discussed for years, and C 1 is thought to be related to the extent of crosslinking . In addition, Hassan et al .…”

Synthesis of poly(acrylic acid)–Fe3+/gelatin/poly(vinyl alcohol) triple‐network supramolecular hydrogels with high toughness, high strength and self‐healing properties

“…Multi‐network hydrogels differ from traditional single interpenetrating network hydrogels. They exhibit a synergy effect between the multiple networks, making their mechanical properties superior to those of hydrogels formed from a single network . Many hydrogels with excellent properties have been prepared by multi‐network technology.…”