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 (Ti3C2Tx), 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 %.