Continuous Phase Separation Induced Tough Hydrogel Fibers with Ultrahigh Conductivity for Multidimensional Soft Electronics

Conductive hydrogel fibers exhibit great potential in soft robots, bioelectronics, and human–machine interfaces due to the unique combination of electrical conductivity, high water content, tissue-like mechanical properties, and 1D structure. Despite significant advances in hydrogel technologies, the typical conductive hydrogel fibers show low conductivity (<10 S cm⁻¹), weak mechanical properties, and water stability, which makes it challenging to satisfy the requirements of practical applications. Here, a facile strategy is proposed to construct hydrogel fibers with ultrahigh conductivity and toughness by exploiting the synergistic effects of freezing-thawing, salting-out, and drying-annealing. The continuous phase separation induced by the combined processes results in hierarchical structures, promoting the formation of interconnected conductive networks and increasing the fiber's crystallinity and crystal domain size. The prepared conductive hydrogel fibers exhibited ultrahigh conductivity (≈958 S cm⁻¹), excellent mechanical properties (strength (≈6.2 MPa), stretchability (>300%), and toughness (≈10 MJ m⁻²)), high water content (≈75%), outstanding water stability, and fatigue resistance properties. In addition, the processibility of conductive hydrogel yarns and fabrics are demonstrated and their potential application in bioelectronics. Overall, this work presents a preparation strategy for conductive hydrogel fibers, which will facilitate the advancement of soft electronics and may inspire structural construction in other polymers. © 2024 Wiley-VCH GmbH.