Analysis and measurement of carbon nanotube dispersions: nanodispersion versus macrodispersion

Because of their unique mechanical, optical, thermal and electrical properties, carbon nanotubes (CNTs) form the basis for a wide variety of multifunctional devices and materials; many of these applications require that CNTs be dispersed and processed in liquids such as organic solvents, polymer melts or surfactant solutions. One of the most problematic issues affecting the CNT research community is the lack of standards and uniform characterization methods for CNT dispersion. A 2005 NASA-NIST workshop aimed to address this issue and made a clear distinction between 'nanodispersion' of individual CNTs and 'macrodispersion' of CNT bundles. Unfortunately, this distinction has yet to percolate through the CNT dispersion literature. The present article seeks to elucidate and commend these concepts, identify the situations where this difference is most critical, note some scenarios where these concepts have been underutilized and posit experimental and computational characterization methods for quantifying the degree of nanodispersion. Particular attention is devoted to the controversial claims of complete nanodispersion and how such claims may be verified. (C) 2010 Society of Chemical Industry