An Antifreezing/Antiheating Hydrogel Containing Catechol Derivative Urushiol for Strong Wet Adhesion to Various Substrates

Abstract

Tough adhesive hydrogels that can tightly bond to wet tissue/polymer/ceramic/metal surfaces have great potentials in various fields. However, conventional adhesive hydrogels usually show shortterm and nonreversible adhesion ability, as the water component in a hydrogel readily transforms to vapor or ice in response to fluctuation of environment temperature, hindering their applications in extreme conditions such as in freezing Arctic and roasting Africa. For the first time, urushiol (UH), a natural catechol derivative with a long alkyl side chain, is used as a starting material to copolymerize with acrylamide for fabricating adhesive hydrogels, which contain hydrophobic/hydrophilic moieties, antifreezing agent, and adhesive catechol groups. The antifreezer/moisturizer glycerol/water binary solvent dispersed in the hydrogel endows it with antifreezing/antiheating property. The hydrophobic association and π−π interaction from UH moieties of the copolymer greatly improve its mechanical strength (tensile stress: ∼0.12 MPa with strain of ∼1100%, toughness: ∼72 kJ/m 3 , compression stress: ∼6.72 MPa at strain of 90%). The hydrogel can strongly adhere to various dry/wet biological/polymeric/ ceramic/metallic substrates at temperatures ranging from −45 to 50 °C. Under ambient conditions, its adhesion force to porcine skin, glass, and tinplate may reach up to 160, 425, and 275 N/m, respectively. Even stored at −45 or 50 °C for 30 d, the hydrogel still maintains good flexibility and robust adhesion force. It also shows repeatable underwater adhesion to biological tissue, glass, ceramic, plastic, and rubber. This novel antifreezing/antiheating adhesive hydrogel may be applied in extremely cold or hot environments and in underwater conditions.

A Spider‐Silk‐Inspired Wet Adhesive with Supercold Tolerance

“…[42] Meanwhile, the SA (PU@PVP) also pushes the edge of the lowest tolerant temperature of wet adhesives from −45 to −196 °C, transcending the developed room-temperature wet adhesives [3,43] and wet adhesive hydrogels with anti-freezers. [44] In summary, we demonstrated an artificial wet adhesive composed of core-sheath nanostructured fibers that exhibited robust adhesion with supercold tolerance even at −196 °C. The wet adhesion of the SA (PU@PVP) is ascribed to intrinsic strength of the undissolved PU and interfacial adhesion achieved by the dissolving-wetting-adhering process of the dissolved PVP.…”

A super-efficient and biosafe hemostatic cotton gauze with controlled balance of hydrophilicity/hydrophobicity and tissue adhesiveness

“…The catechol compound 1,2-benzenediol-3-(9,11,13-pentadecatrienyl) (USO) was extracted from the raw lacquer provided by Xi'an Raw Paint Research Institute by a reported procedure. 30 Briefly, 1 kg of Chinese lacquer sap was dissolved in 2 L of ethanol under mechanically stirring for 24 h at room temperature, followed by filtration to collect filtrate. From it USO was obtained after ethanol was removed by vacuum-rotary evaporation at 60 °C.…”

Bioinspired Smart Materials With Externally-Stimulated Switchable Adhesion

“…In addition, metals could strengthen the adhesive structure through a self-healing mechanism of metal coordination complexes (Shafiq et al, 2012). Because of its versatility, catechol-containing natural molecules have been used for different applications (Sparks et al, 2012;Panchireddy et al, 2018;Fan et al, 2020). However, to make the adhesion switchable, the interfacial materials have to be modified (Nishida et al, 2013;Narkar et al, 2016).…”