Self-healing PVA/Chitosan/MXene triple network hydrogel for strain and temperature sensors.

Conductive hydrogels have attracted intensive attention for their promising applications in flexible electronics, sensors, and electronic skins. However, extremely poor adaptability under cold or dry environmental conditions along with inferior repairability seriously hinders the development of hydrogels in wearable electronics. Here, a triple network conductive hydrogel (PBCP-MXene) was prepared by proportionally mixing polyvinyl alcohol (PVA), borax, chitosan (CS), phytic acid (PA), and MXene. The prepared triple network hydrogels composed of robust chitosan polysaccharide as the first network, tough PVA biopolymer gel as the second network, and MXene nanosheets as the third network. Facilitated by triple networks, multiple hydrogen bonds, and electrostatic interactions of CS and PA, the obtained hydrogels not only exhibited outstanding mechanical properties (tensile strain of ∼1580 %, stress of ∼280 kPa) and electrical properties (∼ 2.72 S/m), but also possessed excellent self-healing, self-adhesion, anti-freezing and anti-drying properties. This work presents a strategy for the development of biopolysaccharide hydrogels for applications in the field of sensors.