Biomedical Engineering Reference
In-Depth Information
14.8 SEM images of multi-walled CNTs before treatment (a) and after
PMMA plasma polymerization treatment (b) (Gorga et al., 2006).
comparison to neat plasma (Nastase et al., 2006). Chen et al. (2001)
developed an approach based on RF plasma activation, followed by
chemical reactions between derivatized dextran- and plasma-generated
functional groups such as aldehyde groups from acetaldehyde and amino
groups from ethylenediamine. The resulting polysaccharide-grafted CNTs
proved highly hydrophilic.
Multi-walled CNTs were also modified using plasma polymerization with
ethylene glycol (EG) as the monomer (Avila-Orta et al., 2009). The plasma-
polymerized EG-coated CNTs showed very stable dispersion with water,
methanol and ethylene glycol, confirming the hydrophilic behavior of the
treated CNTs. This plasma polymerization technique was successfully used
to produce a plasma poly(methyl methacrylate) (PMMA) coating on CNTs
(Gorga et al., 2006). Excellent suspensions of CNTs were achieved in
toluene after plasma treatment, and plasma PMMA coating was observed
using SEM (Fig. 14.8). The coated CNTs were incorporated into the
PMMA matrix via melt mixing and the mechanical properties of the
nanocomposites formed in this way were determined with tensile measure-
ments. The CNT coating slightly improved the load transfer from the
PMMA matrix to the nanotubes, over the uncoated CNTs, but it did not
significantly influence the dispersion of CNTs. The mechanical properties
were not dramatically improved.
Styrene plasma was also reported to deposit polystyrene (PS) plasma
polymer coating onto multi-walled CNTs (Felten et al., 2007). It was shown
that polystyrene nanocomposite filled with plasma PS-coated CNTs
presented better mechanical properties than the ones filled with unmodified
CNTs (Shi and He, 2004).
Plasma chemical functionalization
CNT sidewalls can be fluorinated via CF
4
plasma treatment (Plank et al.,
2003). Fluorination is one of the most effective modifications of the CNT
