Page 32 - Polymer-based Nanocomposites for Energy and Environmental Applications

Introduction of polymer-based nanocomposites 11

1.3.1.4 Polymer-clay

Nanoclays are introduced as environmentally friendly materials with low-cost chemical
substances. In this field, synthesis, characterization, stability, surface feature, and fab-
rication of polymer/nanoclay are investigated for developing the novel materials. In
polymer/nanoclay composites, the final characteristics are modified rather than bulk
polymer due to particle reinforcing and more restricted movement in polymer chain
as the cross-linking effect. Consequently, some desirable matters such as mechanical
properties, reduction on gas permeability, and flame resistance are achieved as well.
However, nanoclays are ideal for reinforcement due to their high aspect ratio, but they
need to be well dispersed for the appropriate performances [72,73].In this field,the
intercalated nanoclay layered with polymers illustrates the most expected required fac-
tors from the polymer/nanoclay composites. There are various techniques that are car-
ried out in order to intercalate the nanoclays among the polymer matrices such as
mechanical and chemical [74,75].Zabihi etal. [76] investigated the role of montmoril-
lonite nanoclay in self-assembly of quaternized chitosan nanoparticles (QCn) within the
clay layers. The rheological investigations showed that the interfacial interactions
between the QCn-modified clay and epoxy are dominated by the covalent hydrogen
bonding between the amine-/hydroxyl-enriched QCn and the epoxy matrix.
Sari et al. [77] applied surface modification of nanoclay particles by several
amounts of polyester-amide hyperbranched polymer (HBP). The results showed that
the surface modification of the clay particles by HBP made significant enhancement in
corrosion resistance for the epoxy-based coatings.

1.3.2 Polymer-metal nanocomposites

1.3.2.1 Polymer silver nanocomposites
Metal nanoparticles exhibit both high surface area and volume ratio and also active
surface that lead to provide many remarkable properties. Silver (Ag) is mostly known
for its strong toxicity for many microorganisms. Thus, this property makes Ag
nanoparticles more applicable in biomedical and other environmental processes.
Thanks to nanotechnology, polymer/Ag nanocomposites are carried out by using
different synthetic methods such as in situ polymerization [78]. Abbasi et al. [79]
represented a literature article on development in the synthetic techniques of AgNWs,
factors influencing the growth of AgNWs, and their performances in conducting
PNCs. In this field, Wankhede et al. [80] synthesized conducting polyaniline/silver
nanoparticles (PANI-Ag) by in situ polymerization of aniline. In another work
[81], ferroelectric PNCs with silver (Ag) nanoparticles as inclusions were prepared
in order to be evaluated in their dielectric properties and thermal conductivity.

1.3.2.2 Polymer palladium nanocomposites
Many researchers have investigated new methods for the preparation of polymer/
metal nanocomposites in order to eliminate their easy contamination, oxidation,
and aggregation issues. Athawale et al. [82] synthesized Pd-polyaniline by oxidative