Carbon nanoparticle surface functionalisation: converting negatively charged sulfonate to positively charged sulfonamide.
The surface functionalities of commercial sulfonate-modified carbon nanoparticles (ca. 9-18 nm diameter, Emperor 2000) have been converted from negatively charged to positively charged via sulfonylchloride formation followed by reaction with amines to give suphonamides. With ethylenediamine, the resulting positively charged carbon nanoparticles exhibit water solubility (in the absence of added electrolyte), a positive zeta-potential, and the ability to assemble into insoluble porous carbon films via layer-by-layer deposition employing alternating positive and negative carbon nanoparticles. Sulfonamide-functionalised carbon nanoparticles are characterised by Raman, AFM, XPS, and voltammetric methods. Stable thin film deposits are formed on 3 mm diameter glassy carbon electrodes and cyclic voltammetry is used to characterise capacitive background currents and the adsorption of the negatively charged redox probe indigo carmine. The Langmuirian binding constant K = 4000 mol(-1)dm(3) is estimated and the number of positively charged binding sites per particle determined as a function of pH.
Watkins
John D
JD
Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
Lawrence
Ruth
R
Taylor
James E
JE
Bull
Steven D
SD
Nelson
Geoffrey W
GW
Foord
John S
JS
Wolverson
Daniel
D
Rassaei
Liza
L
Evans
Nick D M
ND
Gascon
Silvia Antón
SA
Marken
Frank
F