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Hydrogels have been widely used for adsorbing heavy metal ions in wastewater treatment. Herein, a calcium alginate/poly‐N‐isopropylacrylamide double‐network hydrogel with photothermal responsiveness was prepared for adsorbing heavy metal ions in aqueous solution. The chemical composition, micromorphology, swelling properties, photothermal responsiveness, adsorption properties, and adsorption mechanism of gel microspheres were studied, respectively. The gel microspheres had an interpenetrating three‐dimensional porous structure, and their high porosity morphology and high specific surface area could ensure the adequate exposure of active adsorption sites. The gel microspheres showed excellent selective adsorption of Cr(III), and the theoretical maximum adsorption capacity of 146.16 mg/g was calculated according to the Langmuir model. Besides, its excellent photothermal conversion ability enhanced the resistance to external interference after the adsorption. Our work has provided an innovative approach to solar water purification while optimizing the preparation process. [ABSTRACT FROM AUTHOR]

Conductive hydrogels usually suffer from weak mechanical properties and are easily destroyed, resulting in limited applications in flexible electronics. Concurrently, adding conductive additives to the hydrogel solution increases the probability of agglomeration and uneven dispersion issues. In this study, the biocompatible natural polymer chitosan was used as the network substrate. The rigid network employed was the Cit3−ion crosslinked chitosan (CS) network, and the MBA chemically crosslinked polyacrylamide (PAM) network was used as the flexible network. Tannic acid-reduced graphene oxide (TA-rGO), which has excellent conductivity and dispersibility, is used as a conductive filler. Thus, a CS/TA-rGO/PAM double network conductive hydrogel with excellent performance, high toughness, high conductivity, and superior sensing sensitivity was prepared. The prepared CS/TA-rGO/PAM double network conductive hydrogels have strong tensile properties (strain and toughness as high as 2009 % and 1045 kJ/cm3), excellent sensing sensitivity (GF value was 4.01), a wider strain detection range, high cycling stability and durability, good biocompatibility, and antimicrobial properties. The hydrogel can be assembled into flexible wearable devices that can not only dynamically detect human movements, such as joint bending, facial expression changes, swallowing, and saying, but also recognize handwriting and enable human-computer interaction. [ABSTRACT FROM AUTHOR]