A robust and conductive hydrotalcite/nanocellulose/PVA hydrogel constructed based on the Hofmeister effect.

Conductive hydrogel is one of the basic materials for constructing flexible sensors, and polyvinyl alcohol (PVA) hydrogel is commonly used. However, the current PVA hydrogels have apparent defects in strength and conductivity. The freeze-salting-out process based on the Hofmeister effect can effectively improve the strength of PVA. This study uses hydrotalcite and nanocellulose as additives to construct PVA composite hydrogel using the freeze-salting-out method. Due to the reconstruction of the hydrogen bond and the construction of a multi-level three-dimensional network structure, the tensile strength and elongation of PVA composite hydrogels are improved to 8.2 times and 8.1 times that of the pure PVA hydrogels, respectively. Meanwhile, the conductivity of PVA composite hydrogel is increased by 6.4 times with the significant development of ion content and the effective establishment of the transport path. Based on the characteristics of high ion concentration and stable network structure, the composite hydrogels show excellent elastic and strain recovery properties at -20 °C and room temperature. The prepared composite hydrogels have good biocompatibility. This work realizes the construction of PVA composite hydrogel material with high strength, high conductivity and wide temperature application range. It provides a new idea for the development of flexible biosafety sensors.