Keywords: single-walled carbon nanotubes, CNT, stable dispersion, nanocomposites, functionalisation, purification, environmental health, nanotechnology, solvents
Stable dispersions of single-walled carbon nanotubes
The degree of dispersion of Single-Walled Carbon Nanotubes (SWCNTs) in different solvents is an issue in all studies where applications (in microelectronics, as well as in biological in vitro and in vivo systems) are envisaged. We performed long-term dispersion studies of SWCNTs in four different solvents: phosphate buffer solution (PBS), poly(sodium 4-styrene-sulfonate) (NaPSS), Gum Arabic (GA), and a mixture of dipalmitoylphosphatidylcholine and bovine serum albumin (DPPC/BSA). The dispersion of the composite SWCNT-COOH/polyethylenimine (PEI) in phosphate buffer solution was also investigated. Purification pre-treatments were performed on the samples and checks were made prior to the dispersion studies, to make sure that the chemical treatments did not introduce new functionalities. Similarly, preliminary control studies were performed with SWCNT-COOH/PEI to ensure that the synthesis procedure was correct. We found that GA and DPPC/BSA were the best solvents for the dispersion of the SWCNTs, with the stability of the homogenous solution longer than one month. The dispersion of SWCNT-COOH/PEI in PBS is stable for over six months.