The use of solution viscosity to characterize single-walled carbon nanotube dispersions

A recent report by Agarwal and coworkers (I. Cotiuga, F. Picchioni, U.S. Agarwal, D. Wouters, J. Loos, P. J. Lemstra, Macromol. Rapid Commun. 2006, 27, 1073) has shown that solution viscosity measured in a capillary rheometer can be used to monitor the dispersion quality of SWNTs. They used solution viscosity to determine the optimal sonication time. Their method is compared and contrasted here with other methods used to monitor dispersion quality, and it is argued that it has some advantages over other methods. Specifically, the method of Agarwal and coworkers is quick to apply, and gives a reliable single-parameter measure of the relative quality of a SWNT dispersion.