Understanding the Exfoliation and Dispersion of Hexagonal Boron Nitride Nanosheets by Surfactants: Implications for Antibacterial and Thermally Resistant Coatings

Hexagonal boron nitride (hBN) is a structural analog of graphene, with unique mechanical, thermal, and optical properties that make it desirable for a variety of applications. Production of stable dispersions of well-exfoliated hBN nanosheets, particularly in a nontoxic and inexpensive way, is an important step in the production of hBN macromaterials on an industrial scale. Here, we investigate the use of surfactants for exfoliating and dispersing hBN in aqueous solution. Dispersions in nine different surfactants and water were compared based on dispersion yield, quality, and stability. It was revealed that at low centrifugal force, large-molecular-weight nonionic surfactants disperse the most material. In contrast, when stronger centrifugation is applied, all surfactants produce similar dispersion yields, with dispersions in ionic surfactants containing significantly more exfoliated nanosheets and remaining stable over much longer periods of time. Finally, to demonstrate the scalability and effectiveness of these systems for making macroscopic materials, a dispersion of hBN in sodium dodecyl sulfate (SDS) was used to produce a transparent hBN film that can be deposited on glass and potentially used as an antibacterial or thermally resistant coating.