Rapid Preparation of Antifreezing Conductive Hydrogels for Flexible Strain Sensors and Supercapacitors

Abstract

Conductive hydrogels have shown great promise in flexible electronics, but their practical applications may be impeded by the time-consuming and energy-consuming polymerization process. We proposed a sodium lignosulfonate−Fe (SLS−Fe) strategy to address this challenge and took advantage of carboxymethyl cellulose (CMC) and poly(acrylic acid) to prepare the CMC/PAA/Fe 3+ /LiCl interpenetrating conductive hydrogels with good self-healing properties, antifreezing properties, and a 6fold increase in conductivity in this study. The hydrogel-based flexible strain sensors demonstrated a broad detection range (400%), high sensitivity (GF = 6.19 at 200−400%), and human motion detection capability. The hydrogel-based supercapacitor exhibited a single-electrode specific capacitance of 122.36 F g −1 which successfully powered LEDs. Furthermore, the supercapacitor showed a single-electrode specific capacitance of 83.16 F g −1 at −23 °C (68% of the one exhibited at 25 °C). Therefore, the multifunctional performance of the CMC/PAA/Fe 3+ /LiCl hydrogel is anticipated to play an exemplary role in a new generation of flexible electronics.

Highly Sensitive and Stable Flexible Sensors Based on Antifreezing and Self-Healing Double-Network Composite Hydrogels for Human Motion Monitoring

“…Natural biopolymers with good biocompatibility and renewable properties are considered as ideal materials for the preparation of hydrogels. Gellan gum (GG) is a natural polymer and anionic polysaccharide with the advantages of nontoxicity, biocompatibility, biodegradability, and viscoelasticity, which has a wide range of applications in biomedicine and tissue engineering. , Furthermore, the preparation of interpenetrating double-network hydrogels by blending GG with PAA is an effective strategy to enhance the mechanical properties and biocompatibility of hydrogels. Li et al developed a double-network hydrogel zwitterionic-based flexible sensor interpenetrated by GG/PAAm, which can accurately monitor human motions under a broad temperature range from −40 to 25 °C .…”

Rapid and Controllable Preparation of Multifunctional Lignin-Based Eutectogels for the Design of High-Performance Flexible Sensors

“…To solve this problem, many metal−phenolic chemicals have been reported in recent years. 4,7,18 Among the numerous phenolic candidates, lignin, a natural macromolecular compound containing a large number of reducing methoxy groups and phenolic hydroxyl groups, is one of the best polyphenols to participate in the selfcatalytic system for its biodegradability biocompatibility. 19−21 For example, Sun et al prepared organohydrogels using a lignin-based macromolecular self-catalytic system.…”

“…4 Song et al successfully prepared hydrogels using lignin-coated nano silica and formed a self-catalytic system with metal ions. 7 Rapid preparation of the hydrogels at room temperature such as this has the potential for industrial production.…”

“…Inorganic electrolytes or polyols are usually added to the precursor to give the gel freezeresistance. 4,7,26,27 But this needs to be thought through during the initial designing of the experiment. For example, the addition of the polyols can improve the freeze-resistance of the gel, but its conductivity will be greatly reduced, affecting the gelation process.…”

“…Flexible hydrogel-based sensors have gained more and more attention due to their application scenarios and sensing performance advantages. These devices have been widely applied to artificial electronic skin, – self-powered wearable devices, – health monitoring, – etc. The hydrogels possess unique characteristics different from those of other electronic products, such as high transparency, deformability, environmental friendliness, and good biocompatibility. – More importantly, the resistance and charge-carrier density of the hydrogels can be fine-tuned and optimized using different ionic compounds, compared to the electronic conductivity of the metal sheets and carbon sheets. , …”