MXene‐Based Conductive Organohydrogels with Long‐Term Environmental Stability and Multifunctionality

Abstract

Conductive hydrogels are promising interface materials utilized in bioelectronics for human-machine interactions. However, the low-temperature induced freezing problem and water evaporation-induced structural failures have significantly hindered their practical applications. To address these problems, herein, an elaborately designed nanocomposite organohydrogel is fabricated by introducing highly conductive MXene nanosheets into a tannic acid-decorated cellulose nanofibrils/polyacrylamide hybrid gel network infiltrated with glycerol (Gly)/water binary solvent. Owing to the introduction of Gly, the as-prepared organohydrogel demonstrates an outstanding flexibility and electrical conductivity under a wide temperature spectrum (from −36 to 60 °C), and exhibits long-term stability in an open environment (>7 days). Additionally, the dynamic catechol-borate ester bonds, along with the readily formed hydrogen bonds between the water and Gly molecules, further endow the organohydrogel with excellent stretchability (≈1500% strain), high tissue adhesiveness, and self-healing properties. The favorable environmental stability and broad working strain range (≈500% strain); together with high sensitivity (gauge factor of 8.21) make this organohydrogel a promising candidate for both large and subtle motion monitoring.

Full‐Temperature All‐Solid‐State Ti3C2Tx/Aramid Fiber Supercapacitor with Optimal Balance of Capacitive Performance and Flexibility

“…[3,[6][7][8][9] For traditional PVA-H 2 SO 4 electrolyte, the main obstacle for applicating in electrochemical energy storage is insufficient ion conductivity and icing at low temperatures. [42,43] Therefore, an anti-freezing aqueous electrolyte has been developed by weakening the strong H-bonds interaction between water molecules to reduce the freezing point of the aqueous electrolyte. [44] Dimethyl sulfoxide (DMSO) has a strong polarity, high boiling point and good thermal stability.…”

Ionic Conductive Organohydrogels with Dynamic Pattern Behavior and Multi‐Environmental Stability

“…A small and rare porous structure was observed on the surface of Gel 5:5, which resulted from the depressing of the liquid‐solid phase transition temperature of water caused by DMSO during the freeze‐drying process. [ 21 ] The elements Na and Al were homogeneously distributed in the prepared organohydrogel, which indicated that CMC and Al 3+ could easily pass through the porous structure of the hydrogel, thereby generating a continuous ionic fluid to ensure a stable conductivity.…”

“…Owing to the mixed solution of DMSO and water in the gel, the prepared organohydrogel exhibited excellent anti‐freezing properties and long‐term moisture‐retention properties from the reduced amount of free water in the organohydrogel matrix, resulting from the disruption of the formation of crystal lattices of ice and the evaporation of water. [ 8,21 ] To better evaluate the anti‐freezing and moisture‐retention properties of the organohydrogel, the mechanical stability of the Gel with different types under states of freezing and dehydration was evaluated. The temperatures of the freezing and melting of a organohydrogel were separately obtained using differential scanning calorimetry (DSC) from −90 to 20 °C (Figure 4f).…”

“…The decrease in the freezing point was due to the interaction between DMSO and water molecules, where the hydrogen bonds in the ice crystals were broken, which inhibited the formation of ice crystals (Figure S12, Supporting Information). [ 21 ] In addition, Gel 5:5, with a higher content of DMSO, exhibited a smaller pore size (≈ 17 µm) than that of Gel 7:3 (≈ 27.5 µm), which should be attributed to the ice crystal growth in Gel 7:3 at temperatures below −20 °C. [ 19c ] Owing to the anti‐freezing property of the organohydrogel, mechanical stability in a low‐temperature environment is exhibited.…”

An environment-stable hydrogel with skin-matchable performance for human-machine interface

“…In contrast, the residual mass of the hydrogel without LiCl reduced to only 40%. The water-retention capacity of PAAm-collagen hydrogel in comparison with orther hydrogels was shown in Table S3 [ 41,[48][49][50][51]. Due to the excellent water retention ability, the PAAm-collagen hydrogel still possessed high mechanical property and conductivity after being stored at 25°C for 7 days (Fig.…”