Ultra-Tough and Highly Recoverable Eutectogels Constructed by Binary Deep Eutectic Solvent-Induced Phase Separation

Abstract Deep eutectic solvent (DES)-based eutectogels are promising for flexible electronics due to their high ionic conductivity, nonvolatility, and low cost. However, achieving simultaneously high toughness, large stretchability, and multifunctionality remains challenging. Here, we report a one-step mixed-DES-induced in situ phase separation strategy to realize tough and stretchable poly(N, N-dimethylacrylamide) (PDMA) eutectogels prepared by polymerization of DMA in a mixed solvent composed of tetraethylammonium chloride-ethylene glycol (TEAC-EG) and choline chloride-ethylene glycol (ChCl-EG). PDMA shows poor compatibility with ChCl-EG, producing a polymer-rich dispersed phase that dissipates energy under deformation, thereby strengthening the gel. In contrast, PDMA is highly compatible with TEAC-EG, generating a continuous solvent-rich phase that facilitates stress redistribution and ensures large elasticity. By adjusting the ratio of the two DESs, the degree of phase separation can be precisely tuned, allowing the mechanical performance to be tailored. At 40 wt % DES, the eutectogels achieve a tensile strength of 9.47 MPa, an elongation of 1678%, and a toughness of 107.06 MJ·m–3. The gels further exhibit excellent self-recovery, shape-memory behavior, and stable sensing performance. This mixed-DES-driven phase separation approach provides a pathway for tailoring microstructures and properties in eutectogels, broadening their application potential in high performance flexible devices.