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Kinetics of the Selective Reaction of Diazonium Salts with Single-Walled Carbon Nanotubes in Aqueous Surfactant Solutions Adam J. Blanch, A manda V. Ellis, Claire E. Lenehan, Jamie S. Quinton School of Chemical and Physical Sciences, Flinders University GPO Box 2100, Adelaide SA 5001 Current methods of synthesis for carbon nanotubes (CNTs) usually produce heterogeneous mixtures of different nanotube diameters, thus a mixture of electronic properties. Consequently, many techniques have been developed in attempts to separate nanotubes according to their electronic type, w ith varying degrees of success. One such technique involves the selective chemical reaction of CNTs with electron w ithdraw ing diazonium salts, w here metallic nanotubes are preferentially functionalised due to their higher electron density at the Fermi level.1 Since this reaction requires the nanotubes to be individualised, it is usually carried out in a surfactant stabilised dispersion. Despite the potential offered by such selective reactions as a pathw ay tow ards separation by electronic type, little research has been performed into the reaction kinetics 2,3, likely due to the limited success reported in separating CNTs via this method.4 Here w e present kinetic data for electric arc produced CNTs reacting w ith three different compounds; 4-bromo, 4-nitro and 4carboxy benzenediazonium tetrafluoroborate salts in aqueous solution. The CNTs w ere dispersed by a variety of commonly utilised surfactants, both ionic and nonionic. The selectivity of these reactions was monitored through the reduction of the absorbance of semiconducting S22 and metallic M11 transitions in the UV-vis-NIR spectra of the solutions as the reaction proceeds.3 It w as observed that this selectivity depends heavily on the type of diazonium salt and its concentration, temperature of the reaction, type of surfactant and also on surfactant concentration in some instances. It is clear that for certain combinations of surfactant and diazonium salt the selectivity is markedly improved, particularly in dispersions of the non- ionic surfactants Pluronic F-127 and Brij S- 100. (1) (2) (3) (4) Strano, M. S.; Dyke, C. A.; Usrey, M. L.; Barone, P. W.; Allen, M. J.; Shan, H.; Kittrell, C.; Hauge, R. H.; Tour, J. M.; Smalley, R. E. Science 2003, 301, 1519-1522. Doyle, C. D.; Rocha, J.-D. R.; Weisman, R. B.; Tour, J. M. J. Am. Chem. Soc. 2008, 130, 67956800. Schmidt, G.; Gallon, S.; Esnouf, S.; Bourgoin, J.-P.; Pascale Chenevier Chem. Eur. J. 2009, 15, 2101-2110. Dyke, C. A.; Stewart, M. P.; Tour, J. M. J. Am. Chem. Soc. 2005, 127, 4497-4509.