Heating Efficiency of Debundled Carbon Nanotubes Compared to Carbon Black

摘要

Carbon nanotubes can be used as heat generating sources when stimulated by infrared light. However, nanotubes aggregate significantly, which may reduce thermal output. This paper compares temperature increases for bundled and separated nanotubes in aqueous media. Further, nano-sized carbon black is compared to carbon nanotubes to determine if nanotubes are more efficient heaters. Results Carbon nanotubes have strong absorption in the infrared, where body tissues are most transparent. Due to their high aspect ratio, nanotubes behave as antenna, [1] a property which should increase their efficiency to couple to incident radiation and in turn generate heat. Recent literature has shown that single- wall carbon nanotubes, in the presence of infrared stimulation, are able to generate enough heat to kill cells in vitro. [2] Therefore, the use of nanotubes for highly-localized thermal ablation therapies seems promising. Carbon nanotubes are hydrophobic and bundle easily and this may affect their absorption and heating efficiency, especially in aqueous media. For biological applications, nanotubes are typically functionalized to inhibit bundling; however, this may affect biological response, and for heat comparisons with carbon black, it is appropriate for all materials to be unfunctionalized. Although it has been shown that nanotubes conduct heat better than carbon black [3-5] no results have yet shown that nanotubes generate heat better following infrared absorption than other carbon materials. Surfactants are employed to aid in the dispersion of the nanomaterials although nanotubes could likewise be wrapped with DNA,[6] or polysaccharides. [7]