Improved dispersion of PEG-functionalized carbon nanofibers in toluene

Small-angle light scattering is used to assess the dispersion of poly(ethylene glycol) (PEG)-functionalized carbon nanofibers suspended in toluene. Analysis of these data show PEG-functionalized and untreated nanofibers exhibit hierarchical morphology consisting of small-scale aggregates (small bundles) that agglomerate to form fractal clusters. The bundles consist of multiple tubes possibly aggregated side-by-side. Functionalization has little effect on this bundle morphology. Rather, functionalization inhibits agglomeration of the bundles. For untreated fibers, large agglomerates appear immediately after cessation of sonication, whereas for functionlized nanofibers, the size of agglomerates is substantially reduced and they do not grow over time due to the presence of PEG oligomers on the surfaces of the nanofibers. Functionalization leads to improved dispersion by inhibiting agglomeration, not by disrupting the side-by-side bundles. (C) 2009 Elsevier B.V. All rights reserved.