Preparation of tough and ionic conductive PVA/carboxymethyl chitosan bio-based organohydrogels with long-term stability for strain sensor

Integrating high ionic conductivity and robust mechanical properties into one hydrogel remains challenging to date. In this paper, poly(vinyl alcohol)/carboxymethyl chitosan/tannic acid/NaCl/glycerol (PCTNG) organohydrogel was prepared by introducing tannic acid (TA), NaCl and glycerol (Gly) into poly(vinyl alcohol)/carboxymethyl chitosan (PVA/CMCS) simultaneously. Owing to the multiple hydrogen bonding complexations, the salting-out effect and metal coordination, the PCTNG organohydrogel showed an attractive overall performance with high tensile strength (2.02 MPa), large elongation at break (570.82%), superb ionic conductivity (3.05 S/m), excellent thermoplasticity and thermally assisted self-healing ability. Moreover, the introduction of Gly made PCTNG organohydrogel had high anti-freezing and anti-dehydration properties. The introduction of TA and NaCl endowed PCTNG organohydrogel with anti-bacterial properties. A flexible strain sensor was made based on this organoydrogel and this strain sensor could detect various human activities. This study provided a simple and promising strategy for manufacturing ionic conductive organohydrogel for flexible wearable devices.Graphical abstract