Super Tough and Intelligent Multibond Network Physical Hydrogels Facilitated by Ti3C2Tx MXene Nanosheets

Stretchable and conductive hydrogels have emerged as promising candidates for intelligent and flexible electronic devices. Herein, based on a multibond network (MBN) design rationale, super tough and highly stretchable nanocomposite physical hydrogels are prepared, where 2D Ti3C2Tx MXene nanosheets serve as multifunctional cross-linkers and effective stress transfer centers. Further MXene-poly(acrylic acid) (PAA)-Fe3+ MBN physical hydrogels fabricated through controlled permeation of Fe3+ exhibit prominent and well-balanced mechanical properties (e.g., the tensile strength can reach 10.4 MPa and elongation at break can be as high as 3080%), attributed to the dual cross-linking network with dense Fe3+-mediated coordination cross-links between MXene nanosheets and PAA chains and sparse carboxy-Fe3+ cross-links between PAA chains. Moreover, both conductive MXene nanosheets and numerous ions endow the hydrogels with superior conductivity (up to 3.8 S m-1), strain sensitivity (high gauge factor of 10.09), and self-healing performance, showing great prospect as intelligent flexible electronics.