Ultra‐Tough and Recyclable Ionogels Constructed by Coordinated Supramolecular Solvents

Abstract

The mechanical properties of most hydrogels (ionogels) are considerably affected by covalently crosslinked networks. However, the interactions between solvent/solvent molecules and solvent/polymer chains are usually ignored. Herein, a series of ultra-tough ionogels were prepared via a supramolecular solvent, halometallate ionic liquid, in which cations and coordinating anions form a 3D supramolecular network. The linear polymer chains are physically cross-linked with supramolecular solvents synergistically enhancing the strength (14.3 MPa), toughness (78 MJ m À 3 ), and Young's modulus (55 MPa) of ionogels, effectively dispersing the stress concentration under load, and obtaining better fatigue resistance and higher fracture energy (198 kJ m À 2 ). Furthermore, the reversible crosslinking enables green recovery and recycling of ionogels, simply by water. This strategy shows broad applicability based on a variety of supramolecular solvents and coordinatable polymers.

Underwater Self-Healing and Recyclable Ionogel Sensor for Physiological Signal Monitoring

“…This could be due to the destruction of hydrogen bonds by ethanol, which untangles chain segments in ionogel reversibly. After removing ethanol by heating and drying, the ionogel was formed again because of the recombination of hydrogen bonds . These results indicate the recyclability of the ionogel.…”

“…25,26 Meanwhile, to eliminate the marine pollution caused by discarded flexible devices, degradable or cyclic-utilized gel materials are in demand. 27 Nevertheless, the cross-linked polymer network always maintains its mechanical stability at the cost of degradability and recyclability. 28,29 Thus, it is challenging but of huge significance to synthesize ionogelbased biosensors with both desirable mechanical strength and reversible disassembly/recombination capabilities.…”

“…After removing ethanol by heating and drying, the ionogel was formed again because of the recombination of hydrogen bonds. 27 These results indicate the recyclability of the ionogel. Interestingly, the recycled ionogel had an enhanced mechanical performance than the original ionogel as shown in Figure S14a−e.…”

An ultra-tough and ultra-sensitive ionogel pressure/temperature sensor enabled by hierarchical design of both materials and devices

“…2g), IG 0.825 -AL 0.26% -Zn 18% exhibited outstanding comprehensive properties, including strain, stress, fracture energy, toughness and Young's modulus. 17,25,26,[38][39][40][41][42][43][44] Notably, the fracture strength (21 MPa), Young's modulus (325 MPa) and toughness (102 MJ m −3 ) of IG 0.85 -AL 0.065% -Zn 15% are substantially higher than those of existing ionogels (Fig. 2h).…”

A sticky, thermal tolerant, tough BP@PVP ionogel for epidermal sensors

“…Compared to hydrogels and organogels, ionogels offer unique properties, such as higher ionic conductivity, thermal stability, non-flammability, and nonvolatility, which are derived from the ionic liquid. 9,10 As such, the ionogels have been extensively applied in e-skin, [11][12][13] strain sensors, 14,15 human-activity monitoring, [16][17][18][19] solid electrolytes, 20 personal healthcare, 21,22 stretchable touch panels, 23 etc. Yet, most ionogels exhibit weak mechanical properties, such as low fracture strength, toughness and modulus.…”