Photo-induced healing of stretchable transparent electrodes based on thermoplastic polyurethane with embedded metallic nanowires

The incorporation of self-healing functionalities into stretchable thermoset systems can be associated with challenges such as large accumulation of inelastic strain as a result of repeated stretching or dramatic changes in modulus during repeated damage-self-healing cycles. Here, we successfully fabricate a stretchable and transparent electrode with photo-irradiation mediated self-healing capacity. This electrode was realised using Ag nanowires (AgNWs) and thermoplastic polyurethane (TPU) without employing any of the established dynamic self-healing chemistries. First, the AgNWs deposited on a cured TPU film were irradiated with intense-pulsed-light (IPL) to induce plasmonic heating, resulting in a large enhancement in conductivity and mechanically stable, stretchable transparent electrodes. Subsequent rounds of IPL irradiation were employed to repair the artificial cracks formed on the surface of the AgNW/TPU electrodes and the micro-cracks induced by repeated rounds of stretch-and-release testing. The surface analysis confirmed that both types of defects were successfully repaired by the IPL treatment owing to the enhanced flowability and thermal expansion of TPU during IPL irradiation. Multiple scratching with a cutting knife and healing demonstration revealed that the cracks formed at the same locations were healed repeatedly up to five times.