Enhanced Adsorption Affinity of Anionic Perylene-Based Surfactants towards Smaller-Diameter SWCNTs

We present evidence from multiple characterization methods, such as emission spectroscopy zeta potential, and analytical ultracentrifugation to shed light on the adsorption behavior of synthesized perylene surfactants on single walled carbon nanotubes (SWCNTs) On comparing dispersions of smaller diameter SWCNTs prepared by using cobalt-molybdenum catalysis (CoMoCAT) with the larger-diameter SWCNTs prepared by high pressure carbon monoxide decomposition (HiPco), we find that the CoMoCAT-perylene surfactant dispersions ire characterized by more negative zeta potentials, and higher anhydrous specific volumes (the latter determined from the sedimentation coefficients by analytical ultracentrifugation), which indicates an increased packing density of the perylene surfactants on nano tubes of smaller diameter This conclusion is further supported by the subsequent replacement of the perylene derivatives from the nanotube sidewall by sodium dodecyl benzene sulfonate (SDBS), which first occurs on the larger-diameter nanotubes The en hanced adsorption affinity of the perylene surfactants towards smaller-diameter SWCNTs c in be understood in terms of a change in the supramolecular arrangement of the perylene derivatives on the scaffold of the SWCNTs These findings represent a significant step forward in understanding the non-covalent interaction of pi surfactants with carbon nanotubes, which will enable the design of novel surfactants with enhanced selectivity for certain nanotube species