Purification of boron nitride nanotubes by functionalization and removal of poly(4-vinylpyridine)

BNNTs were functionalized by using a polymer that includes a pyridine group, which can undergo dipole interactions with boron atoms in BNNTs. The functionalized BNNTs were well-dispersed in an alcohol solvent, whereas hexagonal boron nitride impurities precipitated, due presumably to stacked structures. After purification processes, acid was added to a solution that contained functionalized BNNTs to prevent pyridine-boron interactions through stronger acid-base interactions. Thus, the polymer bound to the BNNTs was easily separated, and purified BNNTs could be obtained using a solution process.