Electron paramagnetic resonance as a quantitative tool for the study of multiwalled carbon nanotubes

We have described a method that maximizes the phase separation of graphitic particles (GP) and multiwalled carbon nanotubes (MWNT) in solutions of var ious organic polymeric hosts. This involves the formation of sediment and a solute. These components were characterized for MWNT and GP content using electron paramagnetic resonance (EPR) measurements. All EPR signals could b e deconvoluted into nanotube and GP components. When normalized, these comp onents are representative of the mass of MWNT and GP present. This allows u s to make quantitative measurements of nanotube and GP content in different environments. The most successful polymer host was poly (m-phenylenevinyle ne-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV). In this case the solute c ontained 63% of the added nanotubes with only 2% of the added graphite rema ining. (C) 2000 American Institute of Physics. [S0021-9606(00)70545-X].