Polyethylene glycol grafted chitin nanocrystals enhanced, stretchable, freezing-tolerant ionic conductive organohydrogel for strain sensors

Ionic conductive hydrogels with advantageous mechanical properties and high stretchability attract much attentions in wearable electronic devices. Here, a freezing-tolerant hydrogel with high stretchability (435%), strength (2.0 MPa), and ionic conductivity had been prepared by freezing/thawing of polyvinyl alcohol (PVA) and polyethylene glycol functionalized chitin nanocrystals (PEG-g-ChNCs) in dimethyl sulfoxide-water solvent. The successful grafting of PEG on ChNCs was confirmed by various characterization methods. The organohydrogel reinforced by PEG-g-ChNCs displayed excellent freezing-tolerance without rupture during extension, which remains conductivity (0.01 S/m) even at −20 °C. PVA/PEG-g-ChNCs organohydrogel was employed as strain sensor. Interestingly, the sensors based on this organohydrogel presented high stretching sensitivity with a gauge factor of 2.3, and it could be repeatedly and stably monitor tiny strain under extension and pressure. Therefore, the ionic conductive organohydrogel sensor based PEG-g-ChNCs enhanced PVA have promising applications in wearable devices , such as sports monitoring or healthcare monitoring.