Synthesis of Water-Dispersible Boron Nitride Nanoparticles

Spherical boron nitride nanoparticles with good aqueous dispersibility were synthesized by means of a direct reaction of boric acid and ammonium chloride. The X-ray powder diffraction pattern confirmed the hexagonal BN structure (hBN) with d(002) = 3.33 angstrom. Copper oxide (CuO) was found to affect the morphology and surface properties of the BN nanoparticles. The average size of the spherical h-BN nanoparticles synthesized with the addition of CuO was about 30 nm. The h-BN had a high surface area of 75 m(2)g(-1) and a mesoporous volume of 0.32 cm(3)g(-1). The presence of CuO during the synthesis could enhance the surface electronegativity of the h-BN nanoparticles and change their isoelectric point to pH = 2.7. The zeta potentials of BN were between -30 and -50 mV in the pH range of 4-10. The h-BN nanoparticles were well dispersed and stable in aqueous solution.