Conductive Polyaniline Hydrogel Featuring High Toughness and Low Hysteresis

Polyaniline (PANi) hydrogels have a wide range of applications in artificial skin, flexible robotics, and movement monitoring. Nevertheless, limited by the modulus mismatch between rigid PANi and the soft hydrogel matrix, the high strength and toughness of the PANi hydrogel are mutually exclusive. Although the introduction of sacrificial bonds into the hydrogel network can alleviate this contradiction to a certain extent, it always causes pronounced energy hysteresis during hydrogel deformation. Inspired by the energy storage and release of macroscopic springs, in this work, we propose a molecular entanglement approach for the fabrication of PANi hydrogels featuring high toughness and low hysteresis, where flexible poly(ethylene glycol) (PEG) is entangled with chemically cross-linked poly(acrylic acid) (PAA) as a hydrogel matrix, and rigid PANi as a conductive filler. The resultant PAA/PEG/PANi hydrogel exhibited high mechanical properties (fracture strength of 0.75 MPa and toughness of 4.81 MJ·m⁻³) and a low energy dissipation ratio (28.2% when stretching to 300%). Moreover, the PAA/PEG/PANi hydrogel possesses a good electrical response to external forces and can be employed as a strain sensor to monitor human joint movements by producing specific electrical signals. This work provides a straightforward strategy for preparing tough conductive PANi hydrogels with low hysteresis, showing potential for the development of healthcare devices.