Page 677 - Polymer-based Nanocomposites for Energy and Environmental Applications

622 Polymer-based Nanocomposites for Energy and Environmental Applications

of crystals with polymers trapped within the layers. The double-layered hydroxide-
based nanocomposites are mainly prepared by this method, and it is less developed
for the synthesis of layered silicates. This process is not commonly used for the
synthesis of nanocomposites because high temperature is used for the synthesis
that degrades polymer and the aggregation tendency of the growing inorganic
crystals [6,9].

23.2.6 Nontraditional methods
Many nontraditional methods have also been used for the synthesis of nanocomposites
because to facilitate the better dispersion of the filler in the polymer matrix in order to
achieve improved properties of composites. Researchers have investigated different
routes based on the traditional methods; for example, in situ polymerization can
be customized to be redox [13,14], catalytic chain transfer [15], or photoinduced
polymerization [16]. The other nontraditional methods used for the synthesis of
nanocomposites are microwave-induced [17,18], one-pot synthesis [19-21],
template-directed [22], electrochemical synthesis [23], self-assembly [24,25], and
intermatrix synthesis [26,27].
In one-pot synthesis, a series of reactions are carried out in the same reactor. For
example, synthesis of tin (Sn)-embedded carbon-silica polymer nanocomposites. The
self-assembly involved the spontaneous arrangement of the existing components
followed by the interaction among the components. Eventually, an ordered structure
Q Q
can be obtained; for example, graphene-polymer composites were prepared by -
stacking. The intermatrix synthesis is used to prepare the polymer stabilized metal
nanoparticles. In this method, the polymer matrix must have some functional groups
capable of binding nanoparticles. The microwave-assisted synthesis has several
advantages like rapid volumetric heating, high reaction time, increased reaction
selectivity, and energy-saving behavior [17]. The cellulose’silver nanocomposites
are prepared by using this method [17].

23.3 Different types of green polymer nanocomposites

23.3.1 Polylactic acid (PLA)-based green nanocomposites

It is a thermoplastic and is derived from cornstarch by fermentation. Its basic unit is
lactic acid that is polymerized to polylactic acid by step-wise polycondensation or via
ring opening polymerization of a dilactide intermediate [28-31]. Several tests have
been performed on the PLA and found that it is a suitable matrix for the production
of nanocomposites. Several products are already established in the market; for exam-
ple, Jacob winter (Satzung, Germany) produces biodegradable urns from flax and
PLA by compression molding. Several papers have been published on the optimiza-
tion of natural and man-made cellulose fiber-reinforced PLA composites. Kimura
et al. [32] studied the tensile and bending strength and stiffness volume content
(45%–65%) of ramie fiber-reinforced PLA. It was found that the large content of