Cetyltrimethylammonium Bromide (CTAB) and Dodecyl 
Trimethyl Ammonium Bromide (DTAB) were used to 
non-covalently 
functionalize
 Multi-Walled Carbon 
Nanotubes’ (MWCNTs’) surfaces. Transmission electron 
microscopy analyses evidenced the debundling effects of 
these two cationic dispersants on MWCNT aggregates. 
The intensity of G band relative to D band in Raman 
profiles of MWCNTs does not change substantially after 
the suspension, indicating the majority of the sp2 structure 
of MWCNTs is preserved well. There exists a critical 
concentration for both CTAB and DTAB in suspending 
MWCNTs, i.e. 0.1 g/l, which can be ascribed to the 
formation of dispersant micelles. CTAB is superior to 
DTAB in suspending MWCNTs at a concentration lower 
than the critical one, but a reverse trend is observed when 
the concentration is beyond the critical one; this is 
interpreted in terms of geometric features of alkyl chains.