Preparation of functionalized boron nitride nanosheets by high-gravity liquid phase exfoliation technology

• Two types of f-BNNSs were prepared by high-gravity liquid phase exfoliation technology. • Both methods realized the integration of exfoliation and functionalization. • Both methods did not involve hazardous chemicals and harsh experimental conditions. • Both types of f-BNNSs can be stably dispersed in water for a long time. • Both methods are promising candidates for large-scale production of f-BNNSs. There was great interest in the exfoliation of hexagonal boron nitride to prepare functionalized boron nitride nanosheets (f-BNNSs) directly with high efficiency and ecofriendliness. In this study, a novel method has been demonstrated for the fabrication of two types of f-BNNSs by high-gravity liquid phase exfoliation technology. First, hydroxylated boron nitride nanosheets (OH-BNNSs) were prepared by high-gravity liquid phase exfoliation technology assisted by polyvinyl alcohol as a surfactant. The yield of OH-BNNSs was 1.4%. The average size of OH-BNNSs is approximately 390 nm, and the number of layers is approximately 7−8 layers. Second, The 4−5 layers of aminated and hydroxylated boron nitride nanosheets (NH 2 -OH-BNNSs) with an average size of approximately 136 nm were obtained by combining ammonium bicarbonate-assisted ball-milling pretreatment and high-gravity liquid phase exfoliation technology. The yield of NH 2 -OH-BNNSs was 8.5%. Both types of f-BNNSs can be stably dispersed in water. The similarities and differences in morphology and structure between them were confirmed by characterizations. Both preparation processes do not involve hazardous chemicals and harsh reaction conditions. Therefore, this work provides good ideas for simple and efficient preparation of f-BNNSs, which is conducive to their selective applications according to their characteristics.