Assembly and Characterization of Length-Sorted, Aligned Boron Nitride/Carbon Nanotube Thin Film Composites Via Slow Vacuum Filtration

Globally aligned single-wall carbon nanotubes (SWCNTs) are a promising, scalable platform for studying fundamental physical phenomena and an important vehicle for optoelectronic device applications. Recent work by Rust et al . [1] has identified nanotube length as an important mediating factor in the degree and scale of SWCNT alignment via slow vacuum filtration (SVF). Building on this work and that of Walker et al . [2,3], we explore the co-assembly of length-sorted SWCNTs and boron nitride nanotubes (BNNTs) atop polycarbonate track-etched membranes. BNNTs have recently gained interest as a chirality-agnostic, wide-bandgap material for encapsulation, insulation, thermal/mechanical robustness, and visible-light transparency, while also having a similar high aspect ratio morphology, making them an exceptional and alignable host matrix for individualized CNT species. To prepare such hybrid assemblies, a polymer-assisted, depletion-based method was first used to length-sort different diameter SWCNT (alkane filled electric-arc, CoMoCAT, metallic-sorted Tuball), and BNNT nanotube populations. Thereafter, we investigated the impacts of tube lengths, relative BN/C fraction, mass loading, and presence of a global director force on the multi-scale assembly behavior. A combination of birefringence microscopy and polarized Raman spectroscopy probed and identified trends in global and local ordering under these conditions. [1] Rust, C., Shapturenka, P., Spari, M., Jin, Q., Li, H., Bacher, A., Guttmann, M., Zheng, M., Adel, T., Hight Walker, A. R., Fagan, J. A., & Flavel, B. S. (2022). The Impact of Carbon Nanotube Length and Diameter on their Global Alignment by Dead-End Filtration. Small (forthcoming). [2] Walker, J. S., Fagan, J. A., Biacchi, A. J., Kuehl, V. A., Searles, T. A., Hight Walker, A. R., & Rice, W. D. (2019). Global Alignment of Solution-Based Single-Wall Carbon Nanotube Films via Machine-Vision Controlled Filtration. Nano Letters , 19 (10), 7256–7264. [3] Walker, J. S., Macdermid, Z. J., Fagan, J. A., Kolmakov, A., Biacchi, A. J., Searles, T. A., Walker, A. R. H., & Rice, W. D. (2022). Dependence of Single‐Wall Carbon Nanotube Alignment on the Filter Membrane Interface in Slow Vacuum Filtration. Small , 18 , 2105619.