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Despite the method reported in ref. 35 neither sedimentation nor aggregation of the
MWNTs bundles observed in Sample 1. Presumably, this behavior in Sample 1 can be
attributed to contribution of CHT biopolymer to forms an effective barrier against re-
agglomeration of MWNTs nanoparticles. In fact, using sonication energy, in fi rst step
without presence of solvent, make very tiny exfoliated but unstable particle in water
as dispersant. Instantaneous addition of acetic acid as solvent and long mixing most
likely helps the wrapping of MWNTs strands with CHT polymer chain.
Figure 5.6 shows the FTIR spectra of neat CHT solution and CHT/MWNTs disper-
sions prepared using strategies explained in experimental part. The interaction between
the functional group associated with MWNTs and CHT in dispersed form has been un-
derstood through recognition of functional groups. The enhanced peaks at ~1600 cm
-1
can be attributed to (N-H) band and (C = O) band of amid functional group. However,
the intensity of amid group for CHT/MWNTs dispersion increases presumably due to
contribution of G band in MWNTs. More interestingly, in this region, the FTIR spec-
tra of MWNTs-CHT dispersion (Sample 1) have been highly intensifi ed compared to
Sample 2 [35]. It correlates to higher chemical interaction between acid functionalized
C-C group of MWNTs and amid functional group in CHT.
Figure 5.6.
FTIR spectra of CHT-MWCNT in 1% acetic acid with different techniques of dispersion.
This probably is the main reason of the higher stability and lower MWNTs dimen-
sion demonstrated in Figs. 5.4 and 5.5. Moreover, the intensity of protonated sec-
ondary amine absorbance at 2400 cm
-1
for Sample 1 prepared by new technique is
negligible compared to Sample 2 and neat CHT. Furthermore, the peak at 2123 cm
-1
is
a characteristic band of the primary amine salt, which is associated to the interaction
between positively charged hydrogen of acetic acid and amino residues of CHT. In
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