2, Technion-Israel Institute of Technology and Russell Berrie Nanotechnology Institute (RBNI), Haifa, , Israel
3, National Institute of Aerospace, Hampton, Virginia, United States
4, NASA Langley Research Center, Hampton, Virginia, United States
5, Rice University, Houston, Texas, United States
On the nanoscale, boron nitride nanotubes (BNNTs) exhibit high thermal conductivity, high electrical resistance, high tensile strength, radiation absorption, and high chemical stability to elevated temperatures. With the recent development of high-throughput synthesis techniques and significant strides being made on purification, high-throughput processing routes are needed to translate the nanoscale BNNT properties to the macroscale. This report shows that the superacid, chlorosulfonic acid (CSA), is a good solvent for BNNTs. Cryogenic transmission electron microscopy (cryo-TEM) shows that CSA overcomes the inter-BNNT attractions to separate and dissolve BNNTs, permitting detailed analysis of the as-produced material. As a solvent, CSA can be used in the purification of BNNTs and can be used to produce aerogels and all-BNNT films with controlled dimensions. For these macroscopic articles, CSA is removed by water or an organic solvent after processing. Because these macroscopic articles are not composites with a second phase, they exhibit excellent material properties including the same oxidation resistance and electrical resistance observed on the nanoscale.