(412j) Filled Single-Wall Carbon Nanotubes: Endohedral Volume Control for Improved Nanotube Properties

Liquid-phase processing of single-wall carbon nanotubes (SWCNTs) generally results in the exposure of their core to the environment (opening) due to the energy input necessary for purification and solubilization, and this often affects the SWCNT properties. With aqueous processing, SWCNTs are routinely fill with water, leading to significant redshifts and detrimental broadening of their electronic transitions and fluorescence quantum efficiencies. Selecting empty (end-capped) SWCNTs has historically been the only strategy to avoid these effects, but is a natively low yield process. In this work, adverse filling is prevented by intentionally prefilling the SWCNTs with various linear and cyclic alkanes to serve as passive and highly homogeneous spacers, or with molecules of varying composition to specifically modulate optical properties or the particle density. In contrast to water ingestion, filling the SWCNT core with low dielectric alkanes only weakly affects the electronic structure of the SWCNTs, effectively simulates empty core conditions but at near 100% yield. This yields highly resolved optical spectra with strongly shifted peak positions compared to water filled SWCNTs, and fluorescence efficiencies approaching those of empty SWCNTs. The effects of endohedral control and its applicability to different SWCNT materials and downstream separations will be presented.