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Ionic conductors are promising candidates for fabricating soft electronics, but currently applied ionic hydrogels and organogels suffer from liquid leakage and evaporation issues. Herein, we fabricated a free-liquid ionic conducting elastomer (LFICE) with dry lithium bis­(trifluoromethane sulfonimide) and elastomeric waterborne polyurethane. The resultant versatile LFICE exhibits superior tensile strength (∼4.5 MPa), satisfactory stretchability (>900%), excellent ionic conductivity (8.32 × 10–4 S m–1 at 25 °C), and sensitive strain (3.21) and temperature (2.22% °C–1) response. The LFICE also presents durable environmental stability due to the all-solid-state feature. In the exploration of application prospects, the as-assembled LFICE sensor can precisely and repeatedly detect human motion and temperature changes, demonstrating its potentials in digital medical diagnosis and monitoring; the as-assembled LFICE thermoelectric generator (TEG) shows a high ionic thermovoltage of 4.41 mV K–1, paving a bright path for the advent of self-powered soft electronics. It is believed that this research boosts the facile fabrication of environmental stable stretchable ionic conductors holding great promise in next-generation soft electronics integrated with dual thermo- and strain-response and energy harvesting.

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Waterborne polyurethane has drawn extensive attention due to its environmental friendliness and is widely used in many areas. However, it is still a great challenge to synthesize waterborne polyurethanes with flame retardancy and fast roomtemperature self-healing ability, along with excellent mechanical performance and emulsion stability due to the mutually contradictory nature of these properties. Herein, waterborne polyurethanes containing organic selenium (SWPU-x) from 0.67 to 3.28 wt % were synthesized, which could simultaneously realize flame retardancy and self-healing ability based on the ability to scavenge active free radicals at high temperature and the dynamic switch of diselenide. All these SWPU-x films self-extinguished within 1 s after the ignition in the vertical combustion tests. The limiting oxygen index of SWPU-4 was improved to 28.5% with excellent UL-94 level (V-0) and self-healing efficiency (91.25%, after being healed in the photoreactor for 30 min at room temperature), together with high mechanical properties (tensile strength was 18.5 MPa and elongation at break was 869.63%), and the total heat release (THR) for SWPU-4 (49.28 MJ/m 2 ) could decrease to 23.80% of the THR for the original waterborne polyurethane WPU (64.67 MJ/m 2 ). This work discovered a new flame-retardant element (organic selenium) and studied its flame-retardant behaviors and self-healing function simultaneously, which would extremely extend the application of waterborne polyurethanes.

Ionic conductors, such as hydrogels, ionogels, and eutectogels, have attained considerable research interest in various advanced application scenarios. However, such ionic conductors still suffer from the restriction of inherent liquid compositions, which may leak or evaporate. Herein, inspired by the control strategy of desertification caused by soil erosion, a novel internal‐external dual enhancement design strategy, i.e., increasing the interaction between the filler itself and its matrix, is proposed to firmly embed the deep eutectic solvent (DES) into polyurethane (PU) to prevent liquid leakage, such that the prepared ionic conductive elastomers (PU‐DESs) are quasi‐solid. The PU‐DESs exhibit marvelous versatility including high stretchability, tensile strength, toughness, self‐healing efficiency, antibacterial ability, ionic conductivity, and excellent freezing tolerance. More intriguingly, benefiting from their quasi‐solid feature, PU‐DESs are endowed with long‐term environmental stability. Thanks to these superb versatile features, PU‐DESs are further successfully applied in the wearable sensor and triboelectric nanogenerator (TENG) for monitoring human motions and converting mechanical energy into electrical energy, breaking away from the limitations of previous most soft iontronics such as liquid leakage or evaporation and weak mechanical strength. Hence, this study establishes an effective material design strategy for various soft iontronics demanding environmental stability and durability.