Ultra-Tough, High-Strength Ionogels Enabling DLP 3D Printing for Wearable Flexible Electronics

Traditional ionogels often suffer from poor mechanical strength and low toughness, which limit their practical use in flexible devices. Although strategies such as constructing double-network and topological structures have improved the toughness of ionogels, their mechanical performance remains insufficient for wearable sensing applications under large stress and strain. To address this challenge, we propose a microphase separation-induced strategy to facilitate the formation of high-density hydrogen bonds. A bicontinuous-phase ionogel was synthesized via a one-step copolymerization method by combining acrylic acid (forming a solvent-rich phase) and a zwitterionic monomer (SPP) (forming a polymer-rich phase), which exhibited differential compatibility with ionic liquids. By leveraging synergistic hydrogen bonding and microphase separation, the ionogel achieves exceptional mechanical performance, with a tensile strength of 7.77 MPa, toughness of 40.24 MJ/m3, and fracture energy of 37.27 kJ/m2, surpassing most reported ionogels while maintaining crack insensitivity. Unlike the conventional ionogels used in sensing, the ionogel developed in this study maintained stable electrical signals even under 1000% strain. Moreover, the strong hydrogen bonding between the polar groups of the SPP segments endows the material with notch insensitivity (the notched samples still sustain 529% strain) and excellent adhesiveness, enabling direct skin contact for tape-free flexible sensors. This study provides a valuable design strategy for advancing ionogels in the field of wearable sensing.