Towards nanostructured boron nitride films

Boron nitride film could be developed for unique thermal management needs that require electrical insulation and also for applications that benefit from the other advantageous properties of boron nitride. In this work the two related major issues on the neat boron nitride films were identified, including the quality of the precursor boron nitride nanosheets (BNNs) and the dispersion of the BNNs relevant to the film fabrication. These issues were explored by examining various solvent systems and experimental conditions for the exfoliation of commercially acquired hexagonal boron nitride into BNNs and their ability to form relatively stable dispersions. The more stable dispersions were used for the fabrication of neat films of BNNs, and the results suggested that the films were too brittle to serve the film functions as those performed by their carbon-based counterparts. As an alternative approach, a small amount of graphene oxides (GOs) was used as binder for BNNs-GOs composite films of significantly improved mechanical characteristics. Thermal and electrical conductivities in these films were evaluated, so was the tuning of the conductivity ratios via thermal annealing of the as-fabricated films. The challenges and opportunities with the development of BNNs-derived neat boron nitride films are discussed, and their potential technological applications are highlighted.