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

Abstract

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.

Mechanistic Insight into the Photo-Oxidation of Perfluorocarboxylic Acid over Boron Nitride

“…The B–O bonds might also correspond to oxygen substitution defects at nitrogen sites (O N ), so both B–O bond formation as edges and point defects are considered in our models. Peaks of N–B (398.1 eV) and N–H (399.0 eV) bonds are found in the N1s peak deconvolution results (Figure c), suggesting the existence of an edge with N–H termination in the commercial hBN as well. The average atomic composition of the commercial hBN was determined to be 45.4 ± 0.3% B, 50.5 ± 0.2% N, and 4.1 ± 0.1% O, where a higher content of N suggests the existence of N B defects in the commercial hBN.…”

Advances in Studies of Boron Nitride Nanosheets and Nanocomposites for Thermal Transport and Related Applications

“…There have been efforts on the use of surfactants, [54][55][56][57][58][59][60][61] polymers and biopolymers, [13,[62][63][64][65][66][67][68][69][70][71][72][73] and large aromatic molecules, [74][75][76][77][78][79] mostly in aqueous media, to improve the exfoliation. For example, sodium cholate and sodium deoxycholate surfactants were found to slightly improve the h-BN exfoliation in water with vigorous sonication, resulting in more concentrated and stable dispersions of exfoliated BNNs.…”

“…For example, sodium cholate and sodium deoxycholate surfactants were found to slightly improve the h-BN exfoliation in water with vigorous sonication, resulting in more concentrated and stable dispersions of exfoliated BNNs. [54] In a more systematic comparison between groups of anionic, cationic, and nonionic surfactants, [61] nonionic surfactants of larger molecular weights were found to be relatively more effective in terms of yielding more concentrated dispersion of BNNs, but the quality of the nanosheets was not so desirable. The conclusion from the study was that the role of the surfactants was primarily in the stabilization of the products from the exfoliation processing in aqueous dispersions, not so much in the exfoliation process itself.…”

“…Vigorous sonication in selected solvents to deliver the required energy represents one of the most popular processing methods for exfoliating h‐BN into BNNs. This technique has been applied independently or in combination with other energy delivery processes or with other exfoliation approaches [26,29,32–79] . For solution/liquid phase exfoliation in general, sonication always plays a major role in the overall processing.…”

Modeling‐Led Materials‐Binding Peptide Design for Hexagonal Boron Nitride Interfaces

“…h-BN nanosheets have many unique properties, for instance, the wide bandgap of 5.5-5.9 eV and high thermal stability which makes it an ideal insulator, [23,24] and can provide an excellent biomedical imaging platform with good biocompatibility. [25][26][27] To obtain h-BN sheets, the exfoliation approach is intriguing, [28][29][30][31] and there is scope for identifying similar biomolecule-mediated strategies via the exploitation of highly specific noncovalent interactions. However, there is very limited knowledge regarding how biomolecules interact with the h-BN surface.…”