Tough, Transparent, and Multifunctional Eutectogels via Coordination-Regulated Monomer Solubilization in Metal-Salt...

Deep eutectic solvent (DES)-based eutectogels are promising soft ionic materials for flexible electronics and wearable sensors, yet their development is fundamentally limited by poor monomer compatibility in conventional Type III choline chloride-based DESs. Tertiary amine-functionalized monomers, such as 2-(dimethylamino)ethyl methacrylate (DMAEMA), exhibit low solubility in these hydrogen-bond-dominated systems due to polarity and interaction mismatches, which prevents uniform precursor formation and controllable polymerization. Here, we introduce a coordination-regulated solvation strategy to overcome this intrinsic limitation. By polymerizing DMAEMA in a Type IV ZnCl_2-acetamide metal-salt DES, Zn^{2 +}-amine pre-coordination regulates the monomer solvation structure, enabling homogeneous dissolution and transparent gel formation. After polymerization, the retained zinc-amine coordination serves as dynamic sacrificial crosslinks that dissipate mechanical energy while preserving network integrity under large deformation. The resulting eutectogels achieve high tensile strength (2.07 MPa), extreme elongation (1957%), ultrahigh toughness (23.40 MJ m^{- 3}), optical transparency (∼80%), autonomous self-healing, and reliable strain- and pressure-sensing responses. This work establishes coordination-regulated solvation in metal salt-based DESs as a general molecular design principle that bridges monomer processability and mechanical robustness in DES-based polymer networks.