Transparent, high-strength, stretchable, sensitive and anti-freezing poly(vinyl alcohol) ionic hydrogel sensors were facilely fabricated for human motion monitoring.

Flexible and conductive hydrogel sensors have great potential for applications in wearable and implantable devices, electronic skin and healthcare diagnosis. However, it remains a great challenge to develop an integrated...

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mame.201900130. Composite HydrogelsCreating load-bearing hydrogels with superior mechanical strength and toughness is of vital importance for promoting the development of polymer hydrogels toward practical applications. Herein, a type of composite hydrogel is facilely fabricated employing simple and effective UV irradiation one-pot method by introducing cheap and available nanosilica sol into hydrophobic association poly(acrylamide-lauryl methacrylate) (HAPAM gels). Composite hydrogels exhibit enhanced mechanical strength (compression stress reaching 4.4 MPa) and toughness (compression hysteresis energy achieved is 151.15 kJ m −3 ) compared to HAPAM gels. Composite hydrogels also demonstrate rapid self-recovery behavior (95.91% stress recovery and 92.19% hysteresis energy recovery after restoration for 15 min, respectively) and favorable fatigue-resistant ability without the help of external stimuli at room temperature based on the cyclic loading-unloading compression measurements. The simple and effective design strategy may help the development of hydrogel materials toward practical applications for soft sensors, tissue engineering, and actuators.The authors declare no conflict of interest. Keywordscomposite hydrogels, fatigue-resistant ability, hydrophobic association poly(acrylamide-lauryl methacrylate), nanosilica sol, rapid self-recovery behavior

Hydrogel-based porous materials have attracted significant attention in the field of oil−water separation due to their oil−water selectivity and low oil adhesion. However, most of the hydrogel-based separation materials have a common problem: poor mechanical properties, no self-healing ability, and narrow application range. Here, the reversible physical interactions in the two networks of poly(vinyl alcohol) (PVA) and poly(acrylamide-co-acrylic acid)/chitosan (P(AM-co-AA)/ CS) are applied to cross-link double-network PVA/P(AM-co-AA)/CS hydrogel (HEPC-Gel). In the new hydrogel system, the synergistic effect of two different physically connected networks promotes HEPC-Gel with outstanding mechanical, self-healing properties, and low swelling ratio. More importantly, HEPC-Gel exhibits an attractive micro−nano rough structure and certain chemical tolerance. As a result, HEPC-Gel-coated mesh (HEG-Mesh) not only shows stable superhydrophilicity/underwater superoleophobicity but also achieves excellent oil−water separation ability (separation efficiency >99%, water flux ≈11 000 L•m −2 •h −1 ). High-performance double-network hydrogels developed in this work provide a new perspective for the application of hydrogel-based porous materials in oil−water separation.

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