Versatile and recyclable conductive hydrogels with long-term environmental adaptability and mechanical stability have attracted tremendous attention in wearable smart electronics. Here, double-network (DN) polyvinyl alcohol (PVA)/cellulose hydrogels were constructed after introducing a conductive rigid cellulose/Zn/Ca network into a soft PVA/borax network. The resultant hydrogels possessed good mechanical and self-adhesive properties, along with transparency, recyclability, and remarkable resistance to freezing. They showed 30-day non-drying properties due to the presence of hygroscopic salts through a dynamic moisture adsorption and desorption process. Dehydrated hydrogels can return to their original states self-regeneration under high relative humidity. Hydrogel-based strain sensors retained good sensitivity and a wide sensing range during the wide working temperature ranging from −40 °C to 50 °C and after recycling. Additionally, conductive hydrogels were integrated into triboelectric nanogenerators (TENGs) functioning as energy harvesters for powering electronics. TENGs retained stable electrical outputs even under harsh conditions and after recycling. Hydrogels were also assembled into flexible self-powered biomechanical sensors and tactile sensors. Thermally reversible interactions in composite hydrogels enabled their good recyclability, thereby reducing economic costs and environmental impacts caused by e-wastes. This work demonstrates the great potential of versatile and recyclable hydrogels with good environmental and mechanical stability in wearable smart electronics under harsh conditions.

中文翻译：

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用于恶劣条件下应变传感器和摩擦纳米发电机的多功能且可回收的双网络 PVA/纤维素水凝胶

具有长期环境适应性和机械稳定性的多功能且可回收的导电水凝胶在可穿戴智能电子产品中引起了极大的关注。在这里，将导电的刚性纤维素/Zn/Ca网络引入到柔软的PVA/硼砂网络中，构建了双网络（DN）聚乙烯醇（PVA）/纤维素水凝胶。所得水凝胶具有良好的机械和自粘性能，以及透明度、可回收性和显着的耐冷冻性。由于动态水分吸附和解吸过程中存在吸湿盐，因此它们表现出 30 天不干燥的特性。脱水水凝胶可以在高相对湿度下自我再生恢复到原始状态。基于水凝胶的应变传感器在-40°C至50°C的宽工作温度范围内以及回收后保持了良好的灵敏度和宽的传感范围。此外，导电水凝胶被集成到摩擦纳米发电机（TENG）中，充当为电子设备供电的能量收集器。即使在恶劣条件下和回收后，TENG 仍能保持稳定的电力输出。水凝胶还被组装成灵活的自供电生物力学传感器和触觉传感器。复合水凝胶中的热可逆相互作用使其具有良好的可回收性，从而降低电子废物造成的经济成本和环境影响。这项工作展示了多功能且可回收的水凝胶在恶劣条件下的可穿戴智能电子产品中具有良好的环境和机械稳定性的巨大潜力。