High-Strength Hydrogel Adhesive Formed via Multiple Interactions for Persistent Adhesion under Saline

Abstract

Hydrogel adhesives have been widely used in wet environments. Nonetheless, strong and stable persistent adhesion remains a challenge. Here, we report a facile yet powerful strategy to construct high-strength hydrogel adhesives for durable adhesion in a saline environment. Such a hydrogel consists of two polymer networks: a hydrophobic-associated polyacrylamide network of covalent and noncovalent cross-links and an alginate network cross-linked by divalent cations in saline. Meanwhile, polydopamine nanoparticles formed through in-situ self-polymerization are distributed evenly throughout the system to provide underwater adhesion. A low and controllable swelling rate and high compressive strength of hydrogels can be achieved via this multiple interaction strategy. Ultimately, this strategy contributes to the persistent underwater adhesion of hydrogels, and the decreasing rate of lap-shear adhesion strength of hydrogels is only 24.79 ± 8.01% after saline immersion for up to 21 days. Moreover, good cytocompatibility of hydrogels is helpful for their application in the biomedical field.

Hydrogels for underwater adhesion: adhesion mechanism, design strategies and applications

“…When most materials are exposed to water, a hydrated layer forms on the surface, which severely hinders the bonding between the adhesive and the substrate. [1][2][3] In addition, existing polymer adhesives are subject to water attack in water and can swell to failure. Therefore, the development of underwater adhesives is urgent.…”

Hydrogel adhesive formed via multiple chemical interactions: from persistent wet adhesion to rapid hemostasis

“…3 Existing challenges include the destruction of the hydration layer, the contradiction between the excellent interface adaptability and tough mechanical strength of the hydrogel, and the decrease in adhesion capacity over time dominated by the high swelling properties of the hydrogel. 4,5 Several strategies have been developed to eliminate the barriers of the hydration layer on the surface of the adhesive matrix, such as the construction of chemical bonding between the surface of the hydrogel and the substrate, 6 introducing hydrophobic groups into the hydrogel, 7,8 and rapidly absorbing interfacial water through the dry polymer network of the hydrogel. 9 In order to take advantage of the interface adaptability and the mechanical property for superior persistent adhesion capability, hydrogels with loose polymer chains are usually first applied, and then a denser polymer network is formed by exposure to external environmental stimuli (e.g., UV light, 4 temperature 10 and water molecules 11 ).…”

Sustained delivery of gemcitabine via in situ injectable mussel-inspired hydrogels for the local therapy of pancreatic cancer

“…10 Among them, glasses were selected as one of the major challenging substrates for quantified shear adhesion experiments in this study thanks to the weaker interfacial interactions and lower surface roughness than aluminum. 41,42 A previous work has documented that the OCMC 4 /CMCS 2 hydrogel uncovered a weak biotissue adhesion force (9.74 AE 1.29 kPa) because only aldehyde groups in the OCMC precursor solution were the main elements participating in the solidification behaviors, while the catechol groups endow this hydrogel with superior initial adhesion ability. 32 As illustrated in Fig.…”