Dynamically bonded, tough, and conductive MXene@oxidized sodium alginate: chitosan based multi-networked elastomeric hydrogels for physical motion detection

Biopolymer-based conductive hydrogels (HGs) are promising candidates for preparing environmentally friendly flexible electronics. However, it is still a great challenge to synthesize biopolymer-based tough, self-healable, and fast strain recoverable HGs. Herein, a facile strategy is demonstrated to synthesize stretchable, self-recoverable, conductive, and tough HGs strain sensors through the formation of multi-dynamic interactions (i.e., imine bond formation, hydrogen bonds, ionic bonds, and electrostatic bonds) and strong covalent interactions between MXene (Ti₃C₂T_x), oxidized sodium alginate (OSA), chitosan (CS), polyacrylamide (PAAm), Fe(III) and PEDOT:PSS. Thus, obtaining dynamically and covalently bonded nanocomposite hydrogels (NCHGs) with controllable interfacial interactions exhibited a high mechanical strength (0.91 MPa), toughness (2.99 MJ/m³), stretchability (820 %), elasticity (>600 %) and conductivity (1.31 S/m). In addition, the presence of Fe(III) ions and conducting fillers endows excellent repeatability with high stability in resistance change upon bending or stretching with ultra-broad sensitivity up to 11-gauge factor and consisting lowest resistance change up to 0.5 %.