A fluorine-rich phenolic polyurethane elastomer with excellent self-healability and reprocessability and its applications for wearable electronics

Polyurethane elastomers with covalent adaptable networks (PU-CANs) based on the dynamic urethane bond have attracted remarkable attention owing to their reprocessability, adaptability, and self-healability. However, it is still a formidable challenge to achieve excellent dynamics at low temperatures since the urethane bond energy is usually high. Herein, a fluorinated phenolic polyurethane (FPPU) elastomer with CANs based on phenol-carbamate bonds was successfully designed and prepared. Subsequently, the effects of fluorine atoms on the mechanical properties, thermal stability, reprocessability, and self-healability, surface free energy, and hydrophobicity of the prepared elastomers were systematically investigated. The FPPU elastomer showed notch-insensitivity, remarkable self-healable efficiency (98%), low dynamic dissociation temperature (60°C), excellent reprocessability, and low surface energy (62 MJ m−2) compared with non-fluorinated counterpart phenolic polyurethane elastomer (APPU). Based on the above-mentioned features, FPPU was selected as an elastic substrate to assemble into a triboelectric nanogenerator (TENG) to harvest energy from natural motion. This TENG exhibited an excellent electrical output performance with a peak open-circuit voltage of 103 V, a peak short-circuit current of 4.7 µA and a peak short-circuit charge of 43 nC. In addition, the TENG possessed high self-cleaning and reprocessing efficiency. Furthermore, a stretchable and self-healing composite conductor based on FPPU was fabricated for flexible electronic devices.