The Effect of Crosslinking Degree of Hydrogels on Hydrogel Adhesion

Abstract

The development of adhesive hydrogel materials has brought numerous advances to biomedical engineering. Hydrogel adhesion has drawn much attention in research and applications. In this paper, the study of hydrogel adhesion is no longer limited to the surface of hydrogels. Here, the effect of the internal crosslinking degree of hydrogels prepared by different methods on hydrogel adhesion was explored to find the generality. The results show that with the increase in crosslinking degree, the hydrogel adhesion decreased significantly due to the limitation of segment mobility. Moreover, two simple strategies to improve hydrogel adhesion generated by hydrogen bonding were proposed. One was to keep the functional groups used for hydrogel adhesion and the other was to enhance the flexibility of polymer chains that make up hydrogels. We hope this study can provide another approach for improving the hydrogel adhesion generated by hydrogen bonding.

Natural, Biocompatible, and 3D-Printable Gelatin Eutectogels Reinforced with Tannic Acid-Coated Cellulose Nanocrystals for Sensitive Strain Sensors

“…Figure A displays the different adhesive stress vs strain profiles, revealing an increase in the materials’ tackiness with the amount of TA@CNC added. Figure B, red and blue columns, represents this increasing tendency of tackiness and energy of adhesion . This trend is reasonably expected because the TA that coats the CNCs promotes H-bonding formation and thus enhances the adhesion energy values …”

“…Figure 4B, red and blue columns, represents this increasing tendency of tackiness and energy of adhesion. 52 This trend is reasonably expected because the TA that coats the CNCs promotes H-bonding formation and thus enhances the adhesion energy values. 33 Although the tackiness values of BioeGels are lower than those of recently reported gelatin eutectogels 18 but higher than that of CNC nanocomposite hydrogels, 33,52 the magnitude of the adhesion force of our ionic materials is good enough to be able to adhere to human skin.…”

“…52 This trend is reasonably expected because the TA that coats the CNCs promotes H-bonding formation and thus enhances the adhesion energy values. 33 Although the tackiness values of BioeGels are lower than those of recently reported gelatin eutectogels 18 but higher than that of CNC nanocomposite hydrogels, 33,52 the magnitude of the adhesion force of our ionic materials is good enough to be able to adhere to human skin. 53,54 Figure 4C shows the cyclic adhesion test on porcine skin for the most sticky gel, BioeGel4%, observing an adhesion increase with successive cycles.…”

A Safe-by-Design Approach for the Synthesis of a Novel Cross-Linked Hyaluronic Acid with Improved Biological and Physical Properties

“…The degree of swelling, a gravimetric measure used to study the cross-linking density of a hydrogel, was an essential parameter to evaluate the adhesive and cohesive properties, as well as the drug release. Cross-linking strategies were used to control the rate and the extent of the hydration required to achieve sustained adhesion [ 54 ]. As reported in the literature, high swelling values were related to lower cross-linking densities [ 37 ].…”

Editorial on Special Issue “Advances in Hydrogels”

“…Different crosslinking methods and crosslinking degrees affect the properties of obtained hydrogels. To study the effect of the crosslinking degree on the adhesivity of hydrogels, Li et al prepared polyvinyl alcohol (PVA), polyacrylamide (PAM) and polyvinyl alcohol-bearing styrylpyridinium group (PVA-SbQ) hydrogels through freeze–thaw cycles, thermal crosslinking and photo-crosslinking, respectively [ 4 ]. They found that the adhesion capability of these hydrogels decreased with an increase in the crosslinking degree.…”