Coordination‐Driven Homogeneous Eutectogel With Simultaneous Ultrahigh Toughness and Optical Transparency

ABSTRACT

Deep eutectic solvent (DES)‐based eutectogels are promising ionotronic materials; however, achieving high mechanical toughness and optical transparency simultaneously remains challenging, as conventional reinforcement strategies typically rely on phase separation that inevitably induces structural opacity. Here, we report a coordination‐driven homogeneous eutectogel constructed via copolymerization of hydroxyethyl methacrylate (HEMA) and 1‐vinylimidazole (VI) in a ZnCl ₂ –acetamide (AcAm) Type IV DES, where ZnCl ₂ serves as both solvent component and intrinsic coordination cross‐linking precursor, enabling a uniform network without additional metal salts. Strong Zn ²⁺ –imidazole coordination acts as dynamic cross‐linking points within the PHEMA‐based network, forming a hybrid structure capable of efficient energy dissipation. At an optimized 30 wt% copolymer content with a HEMA:VI ratio of 6:4, the eutectogel exhibits ultrahigh transparency (> 90%), high tensile strength (6.99 MPa), large elongation at break (1770%), and a toughness of 85.01 MJ m ⁻³ . In contrast, hydrogen‐bond‐dominated ChCl–AcAm systems show negligible strength (< 0.12 MPa), highlighting the essential role of coordination‐mediated reinforcement. Furthermore, abundant coordination and polar interactions endow the eutectogel with robust adhesion. The introduction of BMIMCl ionic liquid further enhances ionic conductivity while preserving mechanical integrity and stable sensing performance. This work demonstrates a coordination‐driven strategy for homogeneous eutectogels combining mechanical robustness and optical transparency.