Flexible nanocomposite paper with superior fire retardance, mechanical properties and electrical insulation by engineering ultralong hydroxyapatite nanowires and aramid nanofibers

With the increasing popularity of modern electronic devices in the fifth-generation (5G) era, high-performance and high-safety electrically insulating materials with good mechanical flexibility and strength, high thermal stability and fire resistance are urgently needed. Herein, we report a highly flexible, thermally stable, and fire-retardant nanocomposite paper with high dielectric breakdown strength and mechanical strength by synergistically integrating one-dimensional ultralong hydroxyapatite (HAP) nanowires and aramid nanofibers (ANFs) through the vacuum-assisted filtration process. The as-prepared HAP/ANF nanocomposite paper has a nanowire/nanofiber networked framework and a layered structure, and exhibits high tensile strength (73.5 MPa), fracture strain (7.4 %), folding durability (1396 times under a loading weight of 9.8 N), excellent flexibility, and good processibility. Notably, the HAP/ANF nanocomposite paper has a superior dielectric breakdown strength (92.4 kV mm−1), high thermal stability and flame retardancy in comparison with the commercial Nomex T410 electrical insulation paper. The multifunctional HAP/ANF nanocomposite paper is promising for applications in miniaturized and flexible electronic devices, high-voltage electrical insulation equipments, and fire-retardant and high-temperature fields.