Hybrid hexagonal-boron nitride/boron nitride nanotube ceramic fiber produced from a novel solution spinning method

Boron nitride (BN) fibers have been studied for the past 50 years, but currently no BN fibers are commercially available. Herein, a system is developed to solution spin boron oxide (BO) with a sacrificial polymer, polyacrylonitrile (PAN). Through conversion in ammonia up to 1100 °C, hexagonal-BN (h-BN) fibers are produced. By adding boron nitride nanotubes (BNNTs) into the spinning solution, h-BN/BNNT hybrid fibers were produced after heat treatment. These hybrid fibers have a tensile strength of 105 MPa and modulus of 43.7 GPa. The fibers were structurally and chemically characterized using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), wide angle X-Ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, and UV Raman spectroscopy to verify their composition. This work illustrates the ability to produce h-BN/BNNT hybrid fibers through a novel solution-spun BO/BNNT/polymer precursor route. Furthermore, this method of preparing hybrid fibers provides the basis for incorporating other nanomaterials to produce hybrid fiber combinations for a variety of different applications. • Solution-spun polymer/boron oxide precursor fiber was used to produce h-BN fiber. • BNNTs were added to the precursor formulation to produce hybrid h-BN/BNNT fiber. • The best h-BN/BNNT fiber had tensile strength of 105 MPa and modulus of 43.7 GPa. • This study presents a scalable route for producing BN fiber.