Anti-freezing and self-healing nanocomposite hydrogels based on poly (vinyl alcohol) for highly sensitive and durable flexible sensors

For the new generation of wearable flexible electronic devices, it is urgent to achieve higher requirements for the realization of anti-freezing properties. Herein, a strategy was successfully designed to fabricate flexible sensors that could withstand at -30 degrees C. Functional poly(diallyldimethylammonium chloride) (PDDA) were successfully grafted onto the surface of cellulose nanocrystals (CNCs) by electrostatic interaction. As biomass acid, phytic acid (PA) with anti-freezing properties were further introduced as crosslinking agents, poly(vinyl alcohol) (PVA)/CNCs@PDDA/PA (PCP) nanocomposite hydrogels were successfully fabricated through facile freeze-thaw cycle in the water/glycerol binary solvent system. With the increase of PA ratio, the anti-freezing performance of hydrogels is improved obviously. The obtained hydrogels still maintain favorable mechanical strength (1.0 MPa) and self-healing efficiency (85.0%) after healing about 4 h at -30 degrees C. Hydrogels based flexible sensors exhibit fast response time (310.0 ms), wide strain detection range (0.0 600.0%), excellent stability and fatigue resistance, which can also perform excellent human motion signal detection tasks even at -30 degrees C for 24 h. This work paves the way for the application of wearable flexible electronic devices in extreme climate areas.