Antifreeze, Conductive and Flexible Ternary PVA/PVP/SA Hydrogels

Polyvinylpyrrolidone (PVP) has excellent water solubility, biocompatibility and surface activity and has been widely used in medicine, biomedical engineering, cosmetics and food. PVP and its monomers are water-soluble, while cross-linked PVP and its copolymers are insoluble in water but can absorb water and form hydrogels. PVP hydrogels are widely used in medical and biomedical engineering because of their excellent biocompatibility. The current work combined PVP with polyvinyl alcohol/sodium alginate (PVA/SA) to from a ternary antifreeze conductive hydrogel by a repeated freezing–thawing method and ion cross-linking method. During the cross-linking process, the pyrrolidone group was introduced to improve conductivity. The PVA crystallization network and SA ion cross-linking network are interpenetrated, which increases the mechanical properties of the hydrogel network and makes the hydrogel have both frost resistance and conductivity. Thus, the PVA/PVP/SA hydrogels showed good mechanical and electrical properties, with a further modification of ethylene glycol (EG) as the bridging agent; the hydrogels exhibited certain low temperature resistance while maintaining good mechanical and electrical properties at a low temperature. A supercapacitor was constructed by utilizing the ternary PVA/PVP/SA hydrogel as an electrolyte, which revealed a specific capacitance of 7 mF cm^-2 at a current density of 0.5 mA cm^-2, indicating a good prospect in the field of flexible energy storage.