Reversible bonding between polymer chains has been used primarily to induce self-healing of damaged polymers. Inspired by the dynamic nature of such bonding, we have developed a polyurethane equipped with dynamic urea bonds (PEDUB) that has high strength sufficient to make it be freestanding and have a healing capability and self-bonding property. This allowed subsequent heterogeneous multicomponent device integration of electrodes/substrate and light-emitting pixels into a light-emitting device. We first used the PEDUB to individually fabricate a highly stretchable electrode containing Ag nanowires and stretchable composites with ZnSbased particles. They were successfully assembled into a stretchable, waterproof electroluminescent (EL) device even under mild conditions (60 °C for 10 min) owing to the reversible exchange of urea bonds and low glass transition temperature of PEDUB. The assembled device with an AC-driven EL architecture retained excellent EL characteristics even after stretching, submersion in water, and cutting owing to the robust solid-state bonding interfaces induced by the dynamic urea bonds. Consequently, various shapes of the illuminating elastomer and an illuminated picture were realized for the first time using the mosaic-like assembly method. This first demonstration of multicomponent assembly paves the way for future stretchable multifunctional devices.

A pressure sensor based on a composite structure comprising air and polymer fibers is suggested to develop a capacitive pressure sensor that is virtually unaffected by repeated pressurization. Reversibly cross‐linkable urethane (RCU) derived from polybutadiene is newly synthesized for electrospinning, which exhibits the Diels–Alder (DA) reaction under mild conditions. RCU‐based microfibril film is fabricated and it succeeds in welding the intersections of the fibers without a collapse of their shape at mild temperature. This is accomplished via the DA reaction to prevent shearing between microfibrils when physical stress is applied to the film. The porous film is mechanically robust and reacts stably when the film is deformed or pressed. Electrodes are formed on both surfaces of the film using Ag nanowires (AgNWs). Vapor‐assisted partial melting of retro‐DA adducts is used to promote fusion of the polymer through the surface of the AgNWs and implement a robust stretchable electrode. The capacitance changes exceptionally uniformly with the magnitude of the applied pressure and deformation. Using this sensor, its functionality is successfully demonstrated by implementing a pressure sensor array composed of 9 px and measuring the external force applied to the balloon injected with air.

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