Mechanically Strong, Wet Adhesive, and Self-Healing Polyurethane Ionogel Enhanced with a Semi-interpenetrating Network for Underwater Motion Detection

Abstract

The gel-based sensors have developed rapidly in recent years toward multifunctionality. However, there are still some challenges that need to be solved, such as poor mechanical properties and inaccessibility to wet or water environments. To address these issues, we have developed an ionogel with a semi-interpenetrating network structure by adopting poly(vinylidene fluoride-co-hexafluoropropylene) as the linear non-cross-linked network, a double-bonded ionic liquid and double-bonded capped polyurethane as the cross-linked network, and an ionic liquid as the conductive media. The obtained ionogel exhibits tunable mechanical properties (3.67–8.76 MPa) and excellent sensing properties (IG-20, GF = 8.2). The superb environmental stability and self-healing properties of the ionogel were also demonstrated. Meanwhile, adhesion, self-healing, and sensing performance were guaranteed for underwater due to the presence of a large number of C–F bonds. We strongly believe that this ionogel with excellent mechanical properties and underwater communication is expected for monitoring the health of the human body and information transmission in the future.

Ionic skin: from imitating natural skin to beyond

“…Typically, the anion [TFSI] is the most selected hydrophobic conducting ion for ionic liquids. [92][93][94][95][96][97][98][99][100][101][102][103] In addition, hydrophobic polymer skeletons, such as P(VDF-HFP), 94,102 fluorinated polyurethane, 96 fluorinated poly(ionic liquid), 93,95,100 etc., have also been frequently tried for the preparation of water-resistant ionic skin.…”

Transparent, Mechanically Robust, Low-temperature- tolerance, and Stretchable Ionogels Enhanced by Konjac Glucomannan toward Wireless Strain Sensors

“…The introduction of KGM formed a semi-interpenetrating network in the original PAM-co-PAA network, and the functional groups enabled it to enhance the mechanical properties of the ionogel. Xu et al (Xu, Wang, Wen, Wang, & Wang, 2022) adopted polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) as the linear non-cross-linked network in the ionogel, and the strain strength increases with the addition of PVDF-HFP (3.67 MPa to 8.76 MPa) because of an increase in crosslinking points. Wang et al (Wang et al, 2021) involved TEMPO-NFC in the hydrogel with covalently cross-linked polyacrylamide and formed a dual network structure.…”

Skin-mimetic tough polyurethane ionogel for use in soft ionotronics

“…Meanwhile, polyurethane (PU) composed of a polyol soft segment and isocyanate hard segments has been widely adopted as the polymeric backbone of gels or elastomers, for its highly tunable rigidity and elasticity. [32][33][34][35] For example, Junqi Sun et al incorporated ILs into PU networks to fabricate self-healing and extremely durable I-skins based on PU-IL ionogels, which possess superior mechanical strength (1.56 MPa), high elasticity (327%), and low Young's modulus (0.42 MPa); the obtained ionogel-based I-skins exhibit exceptional sensitivity over a wide range of strain (0.1-300%) and pressure (0.1-20 kPa). 36 Yaping Wang et al developed a skin-like ionogel by simply mixing IL and thermoplastic polyurethane (TPU), which possessed a large sensing range of strain (0.1-500%) and temperature (À40 to 100 1C), combined with high transparency (up to 94.3%) and antibacterial properties.…”