Conductive fibres constructed on fully self-healing elastomer fibres via an electrospinning approach

Self-healing polymers have recently emerged as some of the most promising materials for the development of sustainable, tough and flexible wearable optoelectronic devices. However, the development of intrinsically self-healing polymer fibres faces challenges because of their significant surface energy, which results in high susceptibility to rapid intermolecular reactions. Herein, we synthesized a polypropylene glycol-based self-healing polymer composed of urea and urethane polar groups suitable for electrospinning. Unlike their thin-film counterpart, polymer chains’ geometrical confinement in fibres endows them with higher stiffness while maintaining sufficient flexibility. This characteristic endowed our self-healing fibre with a mechanical toughness of up to 27 ± 1.1 MJ m⁻³ at a stretching rate of 100 mm min⁻¹ and a toughness of 27 ± 1.5 MJ m⁻³ at 100 mm min⁻¹ after a self-healing time of 6 hours through chain relaxation and H-bond network reconstruction. As a proof-of-concept, we fabricated a fully self-healing conductive fibre with an initial conductivity of 1.0 × 10⁵ S m⁻² and a stretchability of up to 700%. The deposition of multiwalled carbon nanotubes on top of the self-healing fibres enabled them to sustain the polymer chain's flowability and significant conductivity even after crack repair, which enabled their integration into a capacitive sensor device.