Stretchable, Injectable, and Self-Healing Conductive Hydrogel Enabled by Multiple Hydrogen Bonding toward Wearable Electronics

Abstract

Conducting polymer hydrogels have been employed in diverse fields such as energy storage and bioelectronics, which possess both the mechanical properties of hydrogels and electronic transport properties of conducting polymers. However, the rigid and fragile nature of conducting polymers hinders the long-time stability of the hydrogels and limits their applications in emerging flexible electronic devices. In this work, we have developed a novel type of multifunctional conductive polymer hydrogel, of which high conductivity is integrated with excellent stretchability, injectability, and rapid self-healing capability, by incorporating multiple hydrogen-bonding 2-ureido-4­[1H]-pyrimidinone (UPy) groups as cross-linking points into a brittle polyaniline/poly­(4-styrenesulfonate) (PANI/PSS) network. The formation of the interpenetrating PANI/PSS network offers the hydrogel electronic conduction assisted by ionic transport, showing a conductivity of 13 S/m and a linear response (gauge factor = 3.4) to external strain (≈300%), with accurate and reliable detection of various human motions. Taking advantage of the reversibility of the noncovalent cross-links, the hydrogels can be facilely molded into different shapes and demonstrate a complete self-healing within 30 s upon damage. The combination of supramolecular chemistry with conducting polymers enables multifunctionalities in the conductive hydrogel, providing new insights into the design of advanced functional materials with applications in 3D printing, wearable devices, and flexible electronics.

Self‐Healing, Flexible, and Tailorable Triboelectric Nanogenerators for Self‐Powered Sensors based on Thermal Effect of Infrared Radiation

“…The supramolecular systems are physically reversible based on non‐covalent interactions with rapidly exchanging. [ 28–31 ] Moreover, reversible covalent bonds are relatively stable and robust under ambient conditions, while adaptable under certain stimuli. [ 32–35 ]…”

Properties of conductive polymer hydrogels and their application in sensors

“…Chen et al . introduced multiple hydrogen‐bonding 2‐ureido‐4[1H]‐pyrimidinone (UPy) groups as crosslinking points into PAni/PSS network to form self‐healing hydrogel . Dynamic reversibility of hydrogen bonds is beneficial to energy dissipation and network reconstruction, which is the fundamental mechanism of self‐healing properties of hydrogels [Fig.…”

“…(Reproduced from Ref. , with permission from [2019 American Chemical Society). (d) The Chemical structure of βCD–Ad hydrogel (x, y).…”

“…51,59,60 Chen et al introduced multiple hydrogen-bonding 2-ureido-4[1H]pyrimidinone (UPy) groups as crosslinking points into PAni/ PSS network to form self-healing hydrogel. 61 Dynamic reversibility of hydrogen bonds is beneficial to energy dissipation and network reconstruction, which is the fundamental mechanism of self-healing properties of hydrogels fracture surface at room temperature and show 3600% of the original extensibility. 63 According to Chen et al's recent work, a supramolecular polymeric hydrogel with a host cyclodextrin polymer and a guest a-bromonaphthalene polymer presents a rapidly self-healing property that it takes only a minute to get back to the original state in air without adding addictive.…”

Metal‐Free and Stretchable Conductive Hydrogels for High Transparent Conductive Film and Flexible Strain Sensor with High Sensitivity

“…Conductive hydrogels (CHs) combine the mechanical properties of hydrogels with the electrical properties of conductors, [ 1–3 ] and are potential in an extensive range of applications such as in electronic skin, [ 4–6 ] artificial muscles, [ 7,8 ] human–machine interfaces, [ 9 ] biosensors, [ 10–14 ] actuators, [ 15,16 ] and flexible supercapacitors. [ 17,18 ] Transparency and ultrathin is also important requirements for biomedical electronics when applied in miniature smart electronic products.…”