Dispersible Amine-Functionalized Boron Nitride Nanotubes for Applications in Extreme Environments Encountered in the Aerospace and Defense Industry

Abstract

Boron nitride nanotubes (BNNTs) exhibit exceptional properties such as excellent mechanical strength, high thermal stability, and neutron shielding, making them ideal for applications in extreme environments such as the aerospace and defense industry. However, their strong van der Waals forces and chemical inertness pose challenges for achieving effective dispersion in organic solvents through the functionalization of BNNTs. This study presents an approach to BNNTs functionalization using a two-step plasma process involving sequential treatment with Ar followed by NH₃. In the first step, Ar ions physically collide with BNNTs and induce atomic-level defects on BNNTs. Subsequently, in the second step, these defects induce chemical reactions with radials such as NH* generated from the NH₃ plasma, leading to the formation of amine functional groups. The two-step plasma process led to minimized damage to the nanotubes and an approximately 6-fold increase in amine functional groups compared to raw BNNTs. This two-step plasma process enables the stable dispersion of BNNTs in organic solvents without the use of dispersants. As a result, the two-step plasma process provides a high-concentration and stable functionalization method for BNNTs, thus enhancing their suitability for high-performance applications in harsh conditions such as in the aerospace and defense industry.