Polymer nanocomposites from free-standing, macroscopic boron nitride nanotube assemblies

Here we report the fabrication of free-standing boron nitride nanotube (BNNT) sheets by direct deposition and by vacuum filtration methods, including novel hybrid assemblies with BNNT and carbon nanotubes. Such sheets have enabled production of polymer nanocomposites with high nanotube content. Two example cases, BNNT–epoxy nanocomposites (>30 wt% BNNTs) produced by impregnation of dry sheets and BNNT sheets modified by integration of a thermoplastic polyurethane are described. Related methods have proven advantageous for carbon nanotube composites and, enabled by new technology for large scale BNNT production, such composites have now been realized with BNNTs. This represents an important milestone towards the development of BNNT-based multifunctional composites.