It is highly desirable, although very challenging, to develop self‐healable materials exhibiting both high efficiency in self‐healing and excellent mechanical properties at ambient conditions. Herein, a novel Cu(II)–dimethylglyoxime–urethane‐complex‐based polyurethane elastomer (Cu–DOU–CPU) with synergetic triple dynamic bonds is developed. Cu–DOU–CPU demonstrates the highest reported mechanical performance for self‐healing elastomers at room temperature, with a tensile strength and toughness up to 14.8 MPa and 87.0 MJ m−3, respectively. Meanwhile, the Cu–DOU–CPU spontaneously self‐heals at room temperature with an instant recovered tensile strength of 1.84 MPa and a continuously increased strength up to 13.8 MPa, surpassing the original strength of all other counterparts. Density functional theory calculations reveal that the coordination of Cu(II) plays a critical role in accelerating the reversible dissociation of dimethylglyoxime–urethane, which is important to the excellent performance of the self‐healing elastomer. Application of this technology is demonstrated by a self‐healable and stretchable circuit constructed from Cu–DOU–CPU.

Stretchable conductive fibers are key elements for next‐generation flexible electronics. Most existing conductive fibers are electron‐based, opaque, relatively rigid, and show a significant increase in resistance during stretching. Accordingly, soft, stretchable, and transparent ion‐conductive hydrogel fibers have attracted significant attention. However, hydrogel fibers are difficult to manufacture and easy to dry and freeze, which significantly hinders their wide range of applications. Herein, organohydrogel fibers are designed to address these challenges. First, a newly designed hybrid crosslinking strategy continuously wet‐spins hydrogel fibers, which are transformed into organohydrogel fibers by simple solvent replacement. The organohydrogel fibers show excellent antifreezing (< ‐80 °C) capability, stability (>5 months), transparency, and stretchability. The predominantly covalently crosslinked network ensures the fibers have a high dynamic mechanical stability with negligible hysteresis and creep, from which previous conductive fibers usually suffer. Accordingly, strain sensors made from the organohydrogel fibers accurately capture high‐frequency (4 Hz) and high‐speed (24 cm s−1) motion and exhibit little drift for 1000 stretch–release cycles, and are powerful for detecting rapid cyclic motions such as engine valves and are difficult to reach by previously reported conductive fibers. The organohydrogel fibers also demonstrate potential as wearable anisotropic sensors, data gloves, soft electrodes, and optical fibers.

Polyesters with free functional groups allow facile modifications with biomolecules, which can lead to versatile biomaterials that afford controlled interactions with cells and tissues. Efficient synthesis of functionalizable polyesters is still a challenge that greatly limits the availability and widespread applications of biofunctionalized synthetic polymers. Here we report a simple route to prepare a functionalizable polyester, poly(sebacoyl diglyceride) (PSeD) bearing free hydroxyl groups. The key synthetic step is an epoxide ring-opening polymerization, instead of the traditional polycondensation, that produces poly(glycerol sebacate) (PGS) [1]. PSeD has a more defined structure with mostly linear backbone, more free hydroxyl groups, higher molecular weight, and lower polydispersity than PGS. Crosslinking PSeD with sebacic acid yields a polymer five times tougher and more elastic than cured PGS. PSeD exhibits good cytocompatibility in vitro. Furthermore, functionalization by glycine proceeds with high efficiency. This versatile synthetic platform can offer a large family of biodegradable, functionalized polymers with tunable physiochemical and biological properties useful for a wide range of biomedical applications.

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