Scalable, Low-Cost, Freeze-Resistant Hydrogels by Alkali-Polyphenol-Triggered Polymerization for Low-Temperature...

Area of Science:

• Materials Science
• Polymer Chemistry
• Energy Harvesting

Background:

• Hydrogels are key for flexible electrodes in triboelectric nanogenerators (TENGs).
• Current fabrication methods are costly and lack frost resistance, limiting TENG applications.
• Developing robust, low-cost, and anti-freezing hydrogels is crucial for TENG advancement.

Purpose of the Study:

• To design a novel, scalable, and cost-effective hydrogel with superior anti-freezing properties.
• To investigate the self-catalytic system for rapid hydrogel polymerization.
• To demonstrate the hydrogel's potential in triboelectric nanogenerators (TENGs) and tactile sensing.

Main Methods:

• Utilized a multifunctional alkali-polyphenol (DESL-OH-) self-catalytic system.
• Employed ambient polymerization of α-methacrylic acid (MAA) and hydroxyethyl acrylate (HEA) monomers.
• Fabricated and tested a hydrogel-based TENG (H-TENG) under various conditions, including -40°C.

Main Results:

• Achieved rapid, low-cost hydrogel fabrication (<2 min) with high transparency (>88%) and conductivity (2.8 mS cm-1).
• Demonstrated exceptional cryo-tolerance down to -40°C due to in-situ generated ethylene glycol (EG) acting as an anti-freezing agent.
• Successfully operated an H-TENG at -40°C, providing stable power output (154 V, 1.00 µA) and sensitive tactile sensing.

Conclusions:

• Established an efficient and sustainable method for producing anti-freezing hydrogels without external cryoprotectants.
• The developed hydrogel is suitable for next-generation wearable energy harvesters and sensors.
• The findings offer critical insights into designing functional hydrogels for extreme environments.