Polyacrylic acid-functionalized MXene organohydrogels for high-performance and durable wearable sensors

초록

Practical applications of MXene-based hydrogels have been limited owing to their poor oxidation stability and mechanical performance. To overcome these issues, numerous efforts have been devoted to the surface modification of MXenes, but the optimal type of surface modifier has not been systematically explored. Herein, MXene is modified with diverse polymeric modifiers, including polyphenols (PPs) and linear synthetic polymers (LSPs), and the resulting properties are investigated in relation to their molecular structures. LSPs outperform PPs in improving oxidation resistance and mechanical performance of hydrogels, among which poly(acrylic acid) (PAA) provides the highest overall performance. Subsequently, the PAA-modified MXene hydrogel (PMH) is converted into organohydrogels (PMOH) to enhance mechanical performance and environmental durability. The PMOH exhibits substantially improved mechanical performance, including a tensile strain of 1487.5%, a tensile strength of 750 kPa, and a toughness of 5.27 MJ m(-3) with a tissue-like modulus of 71.9 kPa. The PMOH also shows enhanced conductivity compared with the bare organohydrogel (0.105 to 0.133 S m(-1)), robust adhesion to the skin (55.3 kPa), and outstanding resistance to freezing, dehydration, and oxidation. Owing to these properties, the PMOH is employed as a wearable strain and electrophysiological sensor. This study provides rational insights into the development of durable and high-performance MXene hydrogels for biomedical applications.

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