Load-Bearing Organogels: Hierarchical Anisotropic Composite Structure for High Mechanical Toughness and Antifatigue-Fracture Capability under Extreme Conditions.

Abstract

Gels with excellent mechanical properties and antifatigue-fracture capability are attractive materials for load-bearing applications; however, at extreme temperatures, they still suffer from catastrophic failure caused by freezing- or dehydration-induced crack propagation. Here, we present a series of hierarchical anisotropic composite organogels that are strong yet tough and antifatigue-fracture over a wide temperature range (-30 to 60 °C) through the combination strategies of freezing-casting, annealing, and solvent exchange with polyols. Such a hybrid design endows the gels with anisotropic and hierarchical structures and excellent tolerance to extreme temperatures, thus guaranteeing efficient energy dissipation and crack propagation resistance under both ambient and harsh conditions. For instance, the organogel obtained via solvent exchange with glycerol exhibited high strength (22.6 MPa), toughness (198.0 MJ/m³), fatigue threshold (6.92 kJ/m²), and particularly, a superhigh fracture energy (665.7 kJ/m²), which is even higher than anhydrous elastomers, metals, and alloys. Importantly, these values were further boosted at extreme temperatures, such as fatigue thresholds of 8.01 and 9.77 kJ/m² at -30 and 60 °C, respectively. This work offers an attractive strategy for fabricating gel materials that are reliable for load-bearing applications under extreme conditions.