Morphology of dispersed carbon single-walled nanotubes

Using scattering methods, we determine the morphology of carbon nanotube suspensions over length scales from I nm to 50 mum. We find no evidence of rod-like character at any length. Rather, a network structure of aggregated tubes, similar to that seen in dry samples, is found. These observations have significant implications regarding the use of single-walled nanotubes as a composite reinforcing filler since the network structure has significantly lower modulus than fully dispersed tubes. We also show that it is possible to isolate a rod-like fraction from the aggregated suspension using intense sonication, providing a potential route to fully dispersed nanotubes. (C) 2003 Elsevier Science B.V. All rights reserved.