Tough Underwater Super-tape Composed of Semi-interpenetrating Polymer Networks with a Water-Repelling Liquid Surface

Abstract

Despite recent advances in bioinspired underwater adhesives, achieving tough, fast, and stable adhesion in aqueous environments is still challenging. Here, an underwater super-tape with semi-interpenetrating polymer networks (SIPNs) and a water-repelling liquid surface is synthesized. In the SIPN, the linear chains easily diffuse to adapt to the adherends, and the cross-linked chains provide the super-tape with high dimensional stability. Meanwhile, both the linear and cross-linked chains bear many catechol groups, which can not only vigorously interact with the adherends but also form numerous hydrogen bonds serving as sacrificial bonds in the SIPN. Thus, the super-tape shows both high interfacial adhesion and cohesive energy. Moreover, the super-tape is covered with a water-repelling liquid surface by spraying it with traces of a hydrophobic solvent. It is demonstrated that the hydrophobic solvent absorbed on the surface of the super-tape can remove water between the tape and adherends, enabling their intimate contact to form a strong interaction. As such, the super-tape shows excellent instant adhesion property under water, and the adhesive strength and toughness increase with time and reach their maximum values at around 5 h. The maximum debonding energy of the super-tape reaches 3933 J m–2, which is much higher than those of existing double-sided tapes.

Bioinspired Underwater Adhesives

“…For example, Liu et al found that the application of a small amount of hydrophobic solvent (e.g., chloroform and methyl benzoate) on the surface of a catechol-based elastomer (≈0.3 mg cm -2 ) increased the underwater adhesion strength of the material (≈0.9 MPa). [24] It was demonstrated that the hydrophobic solvent absorbed on the surface of the tape can soften the polymers and repel the hydration layer on the adherend, thereby enabling their close contact to form strong interactions (Figure 9a).…”

“…Reproduced with permission. [ 24 ] Copyright 2020 American Chemical Society. b) Underwater adhesive hydrogels with a hydrophobic surface.…”

“…[21][22][23] To achieve dehydration at the molecular level (∼nm), hydrophobic organic solvents, monomers, and polymers have been used to remove the hydration layer and facilitate surface wetting, especially for hydrophobic substrates. [24,25] The use of water-absorbing fillers, including inorganic substances and hydrophilic polymers, is an alternative strategy that is widely used for wet surfaces. [26][27][28] At a larger length scale (μm to mm), surface microstructures can promote water drainage to prevent permanent water trapping.…”

Degradable Hydrogel Adhesives with Enhanced Tissue Adhesion, Superior Self‐Healing, Cytocompatibility, and Antibacterial Property

“…The coordinate noncovalent bonds led to a dynamic reversible network where the moduli of hydrogels were frequency-dependent, which could relax at low frequency and become tensile at the high frequency. [26] As G 10 F 0.05 P 0.1 showed the best anti-deformation feature in stress amplitude sweep mode, a study in alternating stress amplitude sweep mode was carried out to test its self-healing property (Figure 3e). Briefly, 36 Pa (much lower than the intersection of G' and G'' of G 10 F 0.05 P 0.1 in Figure 3a) was chosen as minimum stress to keep hydrogels stay in the linear viscoelastic region and 14 000 Pa (much higher than the intersection of G' and G'' of G 10 F 0.05 P 0.1 in Figure 3a) was chosen as maximum stress to completely destroy the network.…”

Mechanically Robust Dual-Crosslinking Elastomer Enabled by a Facile Self-Crosslinking Approach

“…This approach has been used to fabricate coating, adhesives, hydrogels, etc. [ 18 , 19 , 20 , 21 ]. However, this self-crosslinking has not been explored to fabricate dual-crosslinking elastomers.…”