(557b) Modifying Single-Wall Carbon Nanotubes Properties through Endohedral Filling

The achievable properties of single-wall carbon nanotubes (SWCNTs) can be significantly modified by the chemical environment inside of the SWCNT. However, any aqueous phase processing, such as methods used to separate metallic from semiconducting SWCNTs, routinely fills most or all SWCNTs in a population with water. Unfortunately, water, due to its high dielectric constant and reactivity leads to significant redshifts and detrimental broadening of the SWCNT electronic transitions and reduced fluorescence quantum efficiencies. As an alternative, my group recently demonstrated that intentionally prefilling SWCNTs with various linear and cyclic alkanes can be utilized to provide a passive, highly homogeneous and low dielectric environment inside the SWCNTs. This enables achievement of significantly narrowed linewidths and enhanced fluorescence efficiencies approaching those of pristine, empty, SWCNTs. Beyond simple saturated molecules, it is also of interest to fill SWCNTs with molecules of intermediate dielectric constants or specific functionality. Experiments on the effects of filling SWCNTs of two different average diameters with 60+ organic compounds of intermediate dielectric constant demonstrate that multiple factors affect the achievable optical properties for each SWCNT structure – filler combination. These include a strong bulk dielectric effect, but also effects from specific packing of molecules, sieving thresholds, and even filler induced strain on the nanotube lattice. The strength of these effects and their impact on the applicability of processing for controlled filling to different SWCNT materials and downstream separations will be presented.