Dispersion of single walled carbon nanotubes by self assembly of polymers

Dispersion and stability of single walled nanotubes (SWNT) is one of the inhibiting factors affecting their tailorability for various electronic, chemical and mechanical applications. The realization of these applications depends on dispersing the SWNTs in aqueous media by inducing high forces of repulsion among the SWNTs. Steric repulsions are induced between the SWNTs by attaching polyelectrolytes, like poly styrene sulfonate (PSS) and poly allyl amine hydrochloride (PAH). In this work, self assembly technique is employed to attach polyelectrolytes, and thereby enhance the dispersion of SWNTs in aqueous media. The steric forces produced by the attached polyelectrolytes overcome the high van der Waals' force of attraction between the SWNTs and aid in the SWNTs dispersion. Characterization of the dispersions with UV-Vis spectrophotometer in kinetic mode revealed that SWNTs treated at pH 3 are seen to be more stable than the ones treated at pH 7. The effect of pH of the polyelectrolyte solutions in the assembly and its consequence on dispersion stability is also studied with zeta potential measurements. The morphology of the films produced by drying the SWNTs in vacuum on a silicon substrate is characterized by field emission scanning electron microscopy (FESEM).