Design of High-Temperature-Tolerant, Self-Healing, and Antiswelling Ion-Conductive Hydrogels for Reliable Flexible Electronics

Ion-conductive hydrogels (ICHs), combining electrical properties with the mechanical flexibility of tissue-like materials, represent ideal materials for flexible sensor applications. However, the preparation of ICHs that simultaneously exhibit excellent stretchability, toughness, ionic conductivity, self-healing capability, antiswelling properties, and temperature tolerance through simple methodologies remains a notable challenge. In this system, excess methacrylamide (mAM) undergoes self-assembly at room temperature to form hydrophobic domains, effectively inhibiting water-induced swelling (swelling rate of 11% after 7 days). A small amount of acrylamide (AM) forms multiple dynamic hydrogen bonds with the hydroxyl groups of cellulose nanofibers (CNFs) and amide groups of mAM, improving mechanical properties (tensile strength = 554.37 kPa) and endowing the material with self-healing capability (self-healing efficiency = 92.51% ± 0.40% within 3 h). The ionic liquid serves as the conductive medium and water locking agent, endowing the ICH with excellent strain-sensing performance across a wide temperature range (−50 to 80 °C). The strain-sensing range of the ICH reaches 526%, 890%, and 300% at −50 °C, 25 °C, and 80 °C, respectively, with gauge factors being 1.1, 2.7, and 1.7, respectively. The prepared ICH can be employed for the monitoring of human motion under cold and hot conditions, providing a novel solution for flexible sensing.