Dual network hydrogel sensors based on borate ester bond: Multifunctional performance in high conductivity, stretchability, mechanical strength, and anti-freezing properties

Conductive polymer hydrogels have attracted great attention due to their application prospects in the fields of health care monitoring, wearable electronics and soft robots. Developing hydrogel sensors with robust mechanical characteristics, outstanding sensing abilities, the ability to self-heal and adhere effectively is critical, yet it remains a major challenge. Here, we present a simple one-pot method to prepare a dual-network flexible hydrogel based on polyvinyl alcohol (PVA), acrylamide (AM), pyridine-4-boronic acid derivatives (PBAD), and lithium chloride (LiCl). The cross-linked network is established through reversible and dynamic borate ester bonds, hydrogen bonds, electrostatic interactions and coordination bonds, imparting outstanding mechanical and self-healing characteristics to the material. The incorporation of PBAD not only imparts high conductivity (9.84 mS.cm(-1)) and sensitive sensing performance (GF = 13.89) to the hydrogel, but also synergistically improves its elongation (1689 %), tensile strength (0.6 MPa), and toughness (5.74 MJ/m(3)). In addition, based on the participation of LiCl, the hydrogel shows outstanding anti-freezing properties. This work is expected to provide new ideas for the assembly of high performance flexible sensor and to expand their application in electronic skin, wearable devices, and soft actuators.