Multifunctional Hydrophobic Eutectogel for Addressing Coupled Mechanical, Thermal, and Electrical Requirements in Cryogenic Environments

ABSTRACT Extreme‐cold operations are constrained by synergistic material failures, including embrittlement, arrested ion transport, interfacial icing, diminished damping and catastrophic seal leakage. Current engineering is typically countered using a ‘patchwork’ approach of heavy, costly components that introduce new fragilities. Herein, we designed and synthesized a microphase separated hydrophobic eutectogel that retained good stretchability, high damping and continuous ionic conductance from −100°C to 100°C, enabled by a freezing point of −118.7 °C. The strong temperature dependence of Young's modulus was harnessed in two novel applications: a thermally‐actuated smart‐switch and an O‐ring that eliminated cryogenic leakage. By addressing materials‑system constraints in cryogenic environments within a single monolithic medium, this eutectogel simplified system design and enhanced reliability for industrial operation in frigid extremes.