What question did this study set out to answer?

This research aims to develop a rapid, eco-friendly method for fabricating high-performance polyacrylamide hydrogels using a quadruple-functional MXene.

March 13, 2026

Quadruple-Functional MXene Enables Ultrafast, Green Fabrication of High-Performance Polyacrylamide Hydrogels for Flexible Strain Sensors

Key Points

This research aims to develop a rapid, eco-friendly method for fabricating high-performance polyacrylamide hydrogels using a quadruple-functional MXene.
Employed MXene as an initiating accelerator, physical cross-linker, and conductive agent.
Facilitated fast polymerization of acrylamide at ambient temperature in 5 minutes.
Tested the mechanical and electrical properties of the resulting hydrogels.
Conducted cytotoxicity assays to evaluate biocompatibility.
Achieved 1558% elongation at break and 119 kPa tensile strength in MXene/PAM hydrogels.
Demonstrated improved cytocompatibility compared to traditional BIS/PAM hydrogels.
Showed a rapid response time of 35 ms and a gauge factor up to 2.4 for strain sensing.
Exhibited photothermal performance with a temperature increase of 21.8 °C under near-infrared light.

Abstract

Polyacrylamide (PAM) hydrogels are promising candidates for flexible wearable sensors but suffer from limitations including toxic cross-linkers(N,N′-methylenebis(acrylamide), BIS), prolonged gelation times, high-temperature requirements, and inadequate mechanical properties. Herein, a quadruple-functional MXene was employed to fabricate high-performance PAM hydrogels within 5 min at ambient temperature. MXenes served simultaneously as an initiating accelerator (replacing toxic BIS), physical cross-linker, conductive agent, and reinforcing nanofiller. Reductive MXene nanosheets catalyzed ultrafast polymerization of acrylamide monomers via redox reactions with ammonium persulfate(APS), facilitating a green, low-energy fabrication process and preventing MXene nanosheets reaggregation within the hydrogel network. By adjusting the MXene content, the optimized hydrogel (6 mg/mL MXene) demonstrated exceptional mechanical performance, with 1558% elongation at break and 119 kPa tensile strength, exceeding traditional BIS/PAM hydrogels (1081% elongation, 74 kPa strength). This enhancement is attributed to the uniform honeycomb-like porous structure and dual-network architecture comprising covalent PAM backbone and physical hydrogen-bonded MXene cross-links. Additionally, the MXene incorporation confers electrical conductivity (0.3 S/m) and photothermal performance, with temperature increase up to 21.8 °C under near-infrared (NIR) irradiation and good photothermal stability. As a strain sensor, the hydrogel exhibits two-stage sensing response with gauge factor (GF) of 1.1 (0–235%) and 2.4 (235–400%), rapid response time (35 ms), recovery time (98 ms), and excellent cyclic stability. In L929 cytotoxicity assays, MXene/PAM hydrogels demonstrate improved biocompatibility compared to BIS/PAM hydrogels. The sensor accurately monitors both large human movements (finger, wrist, bending, handwriting) and subtle physiological activities (pulse and throat vibrations). This study introduces a rapid, eco-friendly method for fabricating multifunctional PAM hydrogels with enhanced mechanical, conductive, photothermal, and biocompatible properties for flexible electronic skin and biomedical devices.

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