An Intrinsic Self‐Healable, Anti‐Freezable and Ionically Conductive Hydrogel for Soft Ionotronics Induced by Imidazolyl Cross‐Linker Molecules Anchored with Dynamic Disulfide Bonds

• Published in: Macromolecular rapid communications. Vol. 45; no. 6; pp. e2300613 - n/a
• Main Authors: Liao, Haiyang, Su, Jiayi, Han, Jieling, Xiao, Tieming, Sun, Xiao, Cui, Guixin, Duan, Xiaofei, Shi, Pu
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.03.2024
• Subjects: anti‐freezing; Aqueous solutions; Bending fatigue; Disulfide bonds; dual‐dynamic reversible network; Electronic equipment; flexible ionic skin; Freezing; Freezing point; Hydrogels; Hydrophobicity; Imidazole; Ion channels; Ion currents; Ionic liquids; Ions; Melting points; Polyacrylic acid; Polymers; self‐healing; Substrates; anti‐freezing; dual‐dynamic reversible network; self‐healing; flexible ionic skin
• ISSN: 1022-1336; 1521-3927; 1521-3927
• DOI: 10.1002/marc.202300613

Hydrogels are ideal materials for flexible electronic devices based on their smooth ion channels and considerable mechanical flexibility. A substantial volume of aqueous solution is required to enable the smooth flow of ions, resulting in the agony of low‐temperature freezing; besides, long‐term exposure to bending/tensile tress triggers fatigue issues. Therefore, it is a great challenge to prepare hydrogels with both freeze‐resistance and long‐term durability. Herein, a polyacrylic acid‐based hydrogel with both hydrophobic interaction and dynamic reversible covalent bonding cross‐linking networks is preparing (DC‐hydrogel) by polymerizing a bi‐functional imidazole‐type ionic liquid monomer with integrated disulfide and alkene bonds (DS/DB‐IL) and an octadecyl methacrylate, achieving self‐healing. The DS/DB‐IL anchored into the polymer backbone has a high affinity with water, reducing the freezing point of water, while the DS/DB‐IL with free ions provides superior ionic conductivity to the DC‐hydrogel. The polyacrylic acid with abundant carboxyl gives hydrogel good self‐adhesiveness to different substrates. Ionotronics with resistance‐type sensors with stable output performance are fabricated and explored its application to joint motion and health information. Moreover, hydrogel‐based sensing arrays with high resolution and accuracy are fabricated to identify 2D distribution of stress. The hydrogels have great promise for various ionotronics in many fields. An olefinic cross‐linker is synthesized to incorporate self‐healing structure (disulfide bond) and anti‐freeze components (imidazole ionic liquid). This cross‐linker is utilized to cross‐link hydrophobically type poly(acrylic acid) (PAA) hydrogels, showing remarkable self‐healing capability and cold‐resistance. The prepared hydrogel can be used in resistive soft ionotronic.