Page 183 - Polymer-based Nanocomposites for Energy and Environmental Applications

156 Polymer-based Nanocomposites for Energy and Environmental Applications

Fig. 5.7 Illustration of the polymer wrapping over MWCNTs via the remarkable
donor-acceptor complexes: (A) schematic image of donor-acceptor complexes between PVDF
chains and individual MWCNT, (B) MWCNTs bundles, (C) PVDF chains, and
(D) PVDF-wrapped MWCNTs.
Reprinted and modified with permission from Yuan J-K, Yao S-H, Dang Z-M, Sylvestre A,
Genestoux M, Bai J. Giant dielectric permittivity nanocomposites: realizing true potential of
pristine carbon nanotubes in polyvinylidene fluoride matrix through an enhanced interfacial
interaction. J Phys Chem C 2011;115:5515 21. Copyright 2011 American Chemical Society.

of the π electron cloud, for MWCNTs being electron-rich while PVDF are electron-
deficient molecules (Fig. 5.7A D).

Two-phase composites and shape of fillers
The dielectric properties of nanocomposites based on different shape fillers are dis-
cussed in this section. Firstly, the dielectric properties of Zn filler-based PVDF
nanocomposites are being discussed. The effect of the orientation of zinc flakes
(ZFs) in parallel and perpendicular directions with respect to the electric field was
studied by Zhang et al. [228]. The results suggested that the interfacial polarization
and hence the dielectric constant were improved with an increase in ZF fraction in
the PVDF polymer, and it was relatively higher for the one in the parallel direction
as compared with that in the perpendicular direction. The highest dielectric constant