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[Display omitted] Hydrogel devices still cannot overcome the dehydration puzzle. This problem can be solved by using green deep eutectic solvents (DES) instead of water, but the formed gel lacks enough strength and functionality. Herein, we successfully assembled a function-integrated stable anhydrous gel in DES system using active MXene as a function-filler. First, Mxene can catalyze the rapid polymerization of monomers at room temperature. Then, it can also assemble/crosslink the gel through strong interactions with the polymer chains, which endow the gel with great stretchability (∼1750%), self-healing (∼100%), conductivity (1.5 × 10-2 S·m−1), and adhesion (∼7 kPa;pigskin). In addition, the gel also inherits the environmental adaptability of DES, which can achieve nearly 100% weight retention at 40 °C, even 80 °C. Importantly, the application potential of stable functionalized gels in ultra-anti-dryness bioelectrodes, self-healing strain sensors, and electric-generators have been explored and successively demonstrated. The rapid fabrication of functional materials in this new solvent system can be extended to other anhydrous polymer gels for on-demand development. [ABSTRACT FROM AUTHOR]

• The asymmetric hydrogel is adjusted and assembled by lignin and cellulose derivatives. • The hydrogel exhibits completely asymmetric adhesion, strength, and electriferous. • The hydrogel-based sensor has excellent skin adaptability and application stability. • The hydrogel can be applied to self-adhesive bioelectrodes and self-powered sensors. Mechanical adaptability, great wearability, application stability, and self-powered sensing characteristics are important requirements for hydrogel-based strain sensors. In this study, a novel double-layer hydrogel was fabricated with asymmetrical adhesion, strength, and electriferous properties. Wherein, the lignosulfonate sodium (LS)-borax mediated bottom hydrogel layer exhibits excellent softness (Young's modulus: ~14.2 kPa) and skin-adhesion (Adhesive strength: ~18.7 kPa) while the quaternary hydroxyethyl cellulose (QHEC) mediated top hydrogel layer demonstrates great mechanical strength (Young's modulus: ~101.3 kPa) and non-adhesive (Adhesive strength: ~2.2 kPa) properties. These complementary asymmetrical adhesion and strength properties endow the hydrogel-based sensor with exceptionally stable sensing performance and adaptive wearability; moreover, the lignocellulosic materials utilization plays a significant role in the designability, antibacterial and biodegradable properties. In addition, the synergy of negative LS (-) and positive QHEC (+) particles enables the double-layer hydrogel great self-powered sensing because of the directional movement of free ions initiated by the external mechanical stimulus. This study presents a hierarchical design idea of wearable electronics, which will have potential applications in many fields from wearable bioelectrodes to self-powered sensors. [ABSTRACT FROM AUTHOR]

The restacking tendency of 2D Ti 3 C 2 T X (MXene) sheets is the main obstacle preventing their application as functional materials in hydrogel. Herein, we fabricated novel ultra-stable 3D MXene-polyacrylamide (PAM) nanocomposite hydrogels inspired by the structure of a spider web. In particular, MXene nanosheets were uniformly located in a gel medium by precise alignment of sonication treatments, followed by the in-situ self-assembly of PAM hydrogel. In this instance, the MXene nanosheets are well-confined and trapped (via strong interactions) by the interwoven spider web-like structure of the PAM chains, which grow in-situ on the surface of the nanosheets. This approach proved effective to solve problems associated with the poor stability of MXene nanosheets in the hydrogel; more prominently, the tight cross-linked structure endows the MXene-PAM hydrogel with anti-compressive and anti-swelling capabilities; the continuous distribution of MXene nanosheets connected by the PAM network creates electron transport pathways and proton transport bridges in the hydrogel. Therefore, the hydrogel can be employed as a temperature and strain sensor or as a component of moist-electric nanogenerator. Image 1 • A temporary alignment and permanent in-situ fixation design was proposed. • Spider web-inspired anti-aggregation robust MXene hydrogel was constructed. • The DFT study predicts the formation for the bionic networks. • The hydrogel can be employed as sensor or moist-electric nanogenerator. [ABSTRACT FROM AUTHOR]