Multi-scale structural engineering enables ultra-strong and tough eutectogels.

Abstract

Achieving simultaneous enhancement of strength, stiffness, and toughness in polymer gels remains a fundamental challenge due to the thermodynamic incompatibility between energy storage and energy dissipation. Here, we present a multi-scale regulation approach that synergistically integrates directional annealing with deep eutectic solvent-mediated solvent exchange to precisely modulate the polymer network at molecular, nanoscale, and microscale levels. This coordinated hierarchical design yielded poly(vinyl alcohol) eutectogels exhibiting exceptional tensile strength of 62.2 ± 1.8 MPa, a Young's modulus of 355.3 ± 32.9 MPa, and a toughness of 179.0 ± 11.1 MJ m^-3, representing 311-, 11843-, and 597-fold enhancements over the original hydrogel, respectively. The synergistic effects of enhanced interchain hydrogen bonding, crystalline domain formation, and anisotropic network alignment enabled high fracture resistance (131.5 ± 2.3 kJ m^-2), fatigue threshold of 15.9 kJ m^-2, and damping efficiency of 95.8%, providing robust protection against impact-induced damage. The multi-scale regulation strategy not only offers a promising solution to overcome the conventional trade-offs in mechanical properties, but also establishes universal principles for the design of next-generation soft materials, with significant potential for applications in flexible electronics, wearable devices, and advanced impact-resistant systems.