Due to the low mechanical strength, poor tensile property, and inability to work under extreme conditions, hydrogels encounter obstacles in their practical applications. It was found that the Hofmeister effect could strengthen and toughen the single hydrogel networks. Herein, poly (vinyl alcohol) (PVA)/gelatin dual-network (DN) hydrogels with strong mechanical properties were prepared and improved by Hofmeister effect using NaSO as the salting-out solution. The hydrophilic anion SO induced a salting-out effect, which made the interplay in PVA and gelatin stronger, and the network structure more compact and stable. Moreover, the dual-assisted effect of freeze-thaw and freezing salting-out further enhanced the mechanical properties. The as-obtained DN hydrogel had excellent overall mechanical properties with a fracture tensile strain, a tensile strength and a toughness of 1281 %, 1.12 MPa and 7.19 MJ/m, respectively. In addition, it had the ability to withstand weights more than 5000 times its own mass. The hysteresis energy, Young's modulus, and toughness recovery of the hydrogel reached 91.21 %, 97.36 %, and 97.47 % of the original values when the interval time was 180 min. Furthermore, after treatment with ethylene glycol /HO solution, the hydrogel was given high temperature resistance, anti-freezing and moisturizing properties, while maintaining its good mechanical properties in a wide temperature range. The weight remained at 84.7 % and 71.45 % of the original weight after one week at 25 °C and 12 h at 60 °C, respectively. This kind of multifunctional DN hydrogel with high mechanical properties will find wider application in the field of flexible electronic devices.

中文翻译：

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多功能 PVA/明胶 DN 水凝胶，通过霍夫迈斯特效应增强机械性能


由于水凝胶机械强度低、拉伸性能差、无法在极端条件下工作，在实际应用中遇到障碍。研究发现，霍夫迈斯特效应可以增强和增韧单一水凝胶网络。本文以Na2SO4为盐析溶液，通过霍夫迈斯特效应制备并改进了具有强机械性能的聚乙烯醇（PVA）/明胶双网络（DN）水凝胶。亲水阴离子SO引起盐析效应，使得PVA与明胶的相互作用更强，网络结构更加致密稳定。此外，冻融和冷冻盐析的双重辅助作用进一步增强了力学性能。所得DN水凝胶具有优异的综合机械性能，断裂拉伸应变、拉伸强度和韧性分别为1281%、1.12MPa和7.19 MJ/m。此外，它还能承受超过自身质量5000倍的重量。当间隔时间为180min时，水凝胶的滞后能、杨氏模量和韧性恢复分别达到原值的91.21%、97.36%和97.47%。此外，经过乙二醇/H2O溶液处理后，水凝胶被赋予了耐高温、抗冻和保湿性能，同时在较宽的温度范围内保持了良好的机械性能。在25℃下放置1周和在60℃下放置12小时后，重量分别保持在原始重量的84.7%和71.45%。这种具有高机械性能的多功能DN水凝胶将在柔性电子器件领域得到更广泛的应用。