Effect of solvent solubility parameter on SWNT dispersion in PMMA

SWNT were dispersed in PMMA in eight different solvents with varying three dimensional solubility parameters. Results show that for achieving good dispersion, the polar component (δp) of the solubility parameter is most important, while the other components, namely dispersive and hydrogen bonding (δd and δh), or the total solubility parameter (δt) do not appear to be so critical. The best SWNT/PMMA dispersion was achieved in nitromethane, the most polar solvent used in this study. SWNT/PMMA samples exhibiting different degrees of dispersion have been studied using Raman spectroscopy. The intensity variations in the Raman radial breathing mode, as well as changes in the tangential (G) and overtone of the disorder (G′) band peak positions are consistent with the qualitative dispersion observations obtained from optical and scanning electron microscopy.