One stone for three birds: One-step engineering highly elastic and conductive hydrogel electronics with multilayer MXene as initiator, crosslinker and conductive filler simultaneously

Conductive hydrogels incorporated with MXene are promising interfacial materials utilized in electronics for human–machine interactions, where MXene nanosheets often act as the multifunctional nanofillers to bring both improved properties and novel functionalities. However, little attention is paid on their contribution to the gelation of MXene-polymer hydrogels. In this work, a new multilayer MXene (m-MXene) initiator and its triple roles in preparing highly elastic and conductive hydrogels are reported. The new m-MXene initiator can generate hydroxyl radical species, verified by electron paramagnetic resonance tests, and initiate the polymerization of a series of vinyl monomers free of light, heat, or co-initiators. On this basis, only by one-step mixing m-MXene and a kind of cationic monomers, the monomers are initiated and simultaneously crosslinked by m-MXene to form a high-quality composite hydrogel within several minutes, displaying integrated merits of high stretchability, elasticity, low hysteresis, adhesiveness, and self-healing performance. Ingeniously, during the gelation, m-MXene is in-situ exfoliated to form well-organized conductive networks, and the steric stability of the polymer further enhances the stability of MXenes. With the combined convenient methods and excellent electromechanical behaviors (e.g., ultrafast responsiveness and an ultrabroad working range), a novel wireless six-pixel Braille typewriter is fabricated based on this conductive hydrogel, unveiling its brilliant prospects for flexible electronics.