Atomic force microscopy imaging of dialyzed single-walled carbon nanotubes dispersed with sodium dodecyl sulfate

Abstract

The existence of excess sodium dodecyl sulfate (SDS) molecules in a single-walled carbon nanotube (SWNT) solution dispersed by hybridization with SDS leads to unstable atomic force microscopy (AFM) imaging. In this study, we demonstrate sequential dialysis against pure water in order to remove excess SDS molecules from an SDS-SWNT hybrid dispersion. A 1:102 volume ratio of SDS-SWNT dispersion to water in the dialysis was found to be effective in realizing stable AFM observations of the SDS-SWNT hybrids despite imperfect filtering of SDS via dialysis. On the other hand, the SDS-SWNT hybrids were stable even when this volume ratio was 1:106. Further, the SDS-SWNT hybrids were present in the solution even when the dialyzed samples were stored for 14 days. Our results reveal that dialysis under optimal conditions enables improved handling of SDS-SWNT hybrids, particularly for stable AFM observations.