The functionalization of nanomaterials has long been studied as a way to manipulate and tailor their properties to a desired application. Of the various methods available, the Billups–Birch reduction has become an important and widely used reaction for the functionalization of carbon nanotubes (CNTs) and, more recently, boron nitride nanotubes. However, an easily overlooked source of error when using highly reductive conditions is the utilization of poly(tetrafluoroethylene) (PTFE) stir bars. In this work, we studied the effects of using this kind of stir bar versus using a glass stir bar by measuring the resulting degree of functionalization with 1-bromododecane. Thermogravimetric analysis studies alone could deceive one into thinking that reactions stirred with PTFE stir bars are highly functionalized; however, the utilization of spectroscopic techniques, such as Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, tells otherwise. Furthermore, in the case of CNTs, we determined that using Raman spectroscopy alone for analysis is not sufficient to demonstrate successful chemical modification.

Hexagonal boron nitride (h-BN), also known as white graphene, presents an unparalleled combination of properties, including superior mechanical strength, good thermal conductivity, a wide band gap, and chemical and thermal inertness. However, because of its aversion to chemical modification, its applications have not progressed as much as those of carbon nanomaterials. In this manuscript, we show the functionalization of hexagonal boron nitride using alkyl halides in strongly reducing conditions (Billups–Birch conditions). The tunability of the Billups–Birch reaction is demonstrated by alkylating hexagonal boron nitride with 1-bromododecane and varying equivalents of Li to BN. We found that using a 1:20 BN/Li ratio yields the highest chemical modification, as demonstrated using thermogravimetric analysis and Fourier transform infrared spectroscopy, and supported by X-ray photoelectron spectroscopy. Imaging of the functionalized h-BN (fh-BN) revealed that its sheets exfoliate better in isopropanol than pristine h-BN, which displays highly stacked nanostructures. Moreover, bearing alkyl chains confers the nanosheets with improved dispersibility in nonpolar solvents, such as dodecane, and allows the formation of hydrophobic films.