One-step, additive-free fabrication of highly stretchable and ultra-tough physical polyvinyl alcohol-based eutectogels for strain sensors

Polyvinyl alcohol (PVA)-based eutectogels are appealing due to their non-volatility, low cost, and superior mechanical properties. However, enhancing their compatibility with deep eutectic solvent (DES) often necessitates complex procedures and the use of hazardous substances. In this work, a highly stretchable and ultra-tough physical eutectogel is fabricated in a single step using partially hydrolyzed PVA. The presence of hydrophobic acetate groups in the PVA disrupts hydrogen bonding among PVA chains, while simultaneously enhancing hydrogen bonding between PVA and DES. The physical eutectogel we obtained exhibits outstanding mechanical properties, including a tensile strength of 6.8 MPa, stretchability of up to 2420 % strain, and ultra-high toughness of 122.3 MJ/m³. It exhibits good ionic conductivity, at 0.15 S/m, and consistently produces reliable resistance signals over a variety of human movements, showcasing its effectiveness in strain sensing. This work lays the foundation for advancing the development and fabrication of robust physical PVA-based eutectogels.