Highly efficient and environmentally friendly microwave-assisted hydrothermal rapid synthesis of ultralong hydroxyapatite nanowires

Abstract Ultralong hydroxyapatite nanowires possess many striking advantages such as high biocompatibility, high flexibility, excellent mechanical properties, high thermal stability, and excellent fire resistance, thus, are promising for applications in various fields. However, the highly efficient, low-cost, and environmentally friendly synthesis of ultralong hydroxyapatite nanowires remains a great challenge. Herein, we report a highly efficient, low-cost, environmentally friendly and energy-saving microwave-assisted hydrothermal strategy for the rapid synthesis of ultralong hydroxyapatite nanowires. This method is based on the green chemistry strategy, using water as the only solvent in the absence of organic solvents. Ultralong hydroxyapatite nanowires with diameters of tens of nanometers and lengths of hundreds of micrometers can be prepared in a short period of time (within 20 min), which significantly shortens the synthetic time by about two orders of magnitude compared with the conventional solvothermal method, showing an ultrahigh efficiency and significant energy saving. Moreover, the as-synthesized ultralong hydroxyapatite nanowires are the ideal raw material for the fabrication of the highly flexible and fire-resistant inorganic paper, which is promising for various applications such as fire-resistant paper documents, and flexible electronic products.