Stabilization and “Debundling” of Single-Wall Carbon Nanotube Dispersions in <i>N</i>-Methyl-2-pyrrolidone (NMP) by Polyvinylpyrrolidone (PVP)

Abstract

We present a simple method to stabilize single-wall carbon nanotube (SWNT) dispersions in N -methyl-2-pyrrolidone (NMP) by polyvinylpyrrolidone (PVP). A significant population of isolated SWNTs as well as small bundles of SWNTs in NMP is obtained by ultrasonic treatment followed by vacuum filtration through glass fiber filters. The resulting dispersions in pure NMP are monitored by photoluminescence (PL) spectroscopy over a period of 3 weeks. The PL intensities of such dispersions decrease with time, suggesting slow microscopic aggregation of nanotubes. However, addition of PVP dramatically improves the stability. In addition, PVP also spontaneously “debundles” some nanotube aggregates, increasing the isolated SWNT population without further ultrasonic treatment.