Zinc-ion engineered Plant-based multifunctional hydrogels for flexible wearable strain Sensors, Bio-electrodes and Zinc-ion hybrid capacitors

Multifunctional hydrogels, particularly with superior mechanical properties and using green/sustainable approaches, have attracted increasing attention because of their many applications and consistency with the green chemistry principle; unfortunately, their effective fabrication process is challenging. In this work, inspired by unique functions in plant-derived components, a multifunctional polyacrylic acid (PAA) hydrogel was innovatively developed using ZnCl2 and biomass-derived materials. Ingeniously, ZnCl2 has multiple functions, in combination with cellulose, lignin, and citric acid (CA), delivering intriguing properties to the hydrogel system. As a solvent system, the ZnCl2 solution has extraordinary H-bonding-donating ability, dissolving cellulose macromolecular chains; subsequently, solubilized cellulose as green reinforced-fillers are added to hydrogel, improving the strength properties, with compression strength of similar to 4.1 MPa, tensile strength of similar to 795.4 kPa, and elongation at break of similar to 620 %. The lignin-ZnCl2 catalysis system imparts a fast PAA gelation process, and the resultant hydrogel has strong/long-lasting/repeatable adhesive strength of 25.5 kPa (on Zn-carbon cloth) in 28 days. Additionally, ZnCl2 can form reversible ionic/electrostatic interactions with both lignin and CA, further improving the adhesive and mechanical properties. As anti-freezing agents, water-retaining agents and conducting medium, ZnCl2 also endows the hydrogel with desirable environmental compatibility and good conductivity (14.2 mS center dot cm(-1)). Furthermore, the presence of plant-based components endows the hydrogel with ultraviolet (UV) blocking, biocompatibility and antibacterial attribute. Significantly, the as-prepared hydrogels are suited for such diverse applications as flexible wearable strain sensors, bio-electrodes and zinc-ion hybrid capacitors (ZHCs), even can efficiently work at -65 degrees C. This study provides a new strategy of engineering multifunctional hydrogels using plant-based functional components, and these hydrogels show promising applications in many emerging areas including electronic skin sensors, health monitoring and energy storage devices.

Automated summary

In this study, a multifunctional polyacrylic acid (PAA) hydrogel was developed using ZnCl2 and biomass-derived materials, exhibiting superior mechanical properties. It has potential applications in emerging areas such as electronic skin sensors, health monitoring, and energy storage devices.