Bioinspired, Recyclable, Stretchable Hydrogel with Boundary Ultralubrication

Abstract

Although hydrogels exhibit excellent low frictional behavior, their friction coefficients cannot meet the requirements for biology, especially at low sliding velocities. Inspired by the natural lubrication mechanism from animals, plants, or even microorganisms, a nonionic surfactant, Tween 80, was introduced into a biofriendly poly­(vinyl alcohol) (PVA) hydrogel to construct a composite hydrogel with ultralubrication. Such a combination endows PVA hydrogels with an ultralow coefficient of friction (10–3 to 10–4) under an extremely low sliding velocity (0.01 mm/s). Tween 80 micelles and aggregates, together with hydrophobic molds, induce rough surfaces and high carbon contents on the surface of the hydrogel, promoting excellent lubrication behavior of the composite hydrogel. In addition to the desirable lubrication, this environmentally friendly composite hydrogel also exhibited excellent flexibility at subzero temperatures, tensile properties, and good recyclability. Additionally, the method of introducing Tween 80 into hydrogels to reduce friction is also effective in chemically crosslinked double-network hydrogels.

Bioinspired Hydrogels as Platforms for Life-Science Applications: Challenges and Opportunities

“…Inspired by natural articular cartilages with excellent mechanical properties and surface lubrication, composite materials were developed by grafting hydrophilic polyelectrolyte brush layers on the surface of hydrogels [88]. A friction reduction was also obtained by introducing Tween 80 into PVA physical or chemical hydrogels [89]. Benzophenone was entrapped on the surface of polydimethylsiloxane, polyvinylchloride, or polyurethane and acrylamide was polymerized by ultraviolet irradiation; a hybrid surface with low friction under very high load conditions was obtained, able to conserve the lubrication and wear performances over 100,000 cycles under a pressure of about 10 MPa [90].…”

A Hydrogen Bonds-Crosslinked Hydrogels With Self-Healing and Adhesive Properties for Hemostatic

“…Hydrogels, which are generated by exploiting covalent and/or noncovalent interactions between polymeric components, have been extensively studied due to their unique “human tissue-like” properties, such as their toughness, permeability, biocompatibility, self-healing ability and wettability ( Li D. et al, 2020 ; Poupart et al, 2020 ; Chen et al, 2021 ; Kim et al, 2021 ). In particular, hydrogels with self-healing ability can spontaneously repair the cracked network when deformation occurs, without external stimuli, and maintain their efficacy and integrity in complex physiological environments; consequently, they have attracted great attention in recent years.…”

Highly stretchable, self-healing elastomer hydrogel with universal adhesion driven by reversible cross-links and protein enhancement

“…14,15 As a leader in DNHs, Gong's team have pioneered the development of DNHs including fabrication theories, construction strategies and strengthening mechanisms. 16 Soon afterwards, a series of DN hydrogels was explored comprising physically crosslinked DNHs, 17 chemically crosslinked DNHs 18 and hybrid crosslinked DNHs 19 with one physically crosslinked network and another chemically crosslinked network. Among these DN strategies, the hybrid crosslinked method combining reversible covalent bonds such as a boron ester bond, 20 Schiff base, 19 acyl hydrazone bond 21 and disulfide bond 22 with invertible noncovalent interactions (electrostatic interaction, hydrophobic association, hydrogen bonds and host–guest interactions and so on) as sacrificial bonds has widely been demonstrated as a desirable way to construct hydrogels with high mechanical strength, stretchability, and toughness as well as good self-healing and adhesive abilities.…”