The name is absent

6.1 Introduction

Organic and inorganic fillers have been extensively used to produce polymer com-
posites. Recently, the interest has shifted to cases where one of the dimensions of
these fillers is of the order of a nanometer [170]. Addition of the nano fillers can
significantly improve the mechanical, thermal, electrical and optical properties as
compared to the pure polymer or the conventional micro- or macro-composites [171].
In addition, since the weight fraction of these additives is low, these nanocomposites
are generally lighter than the conventional composites. Examples include the ‘Nano
sandwiches’ in nature such as bones, shells, and wood [172], polypropylene reinforced
by particulate fibers and polymer/clay nanocomposites [173] like clay montmoril-
lonite fillers in nylon-6 [174]. One of the challenges in the synthesis of polymer∕clay
nanocomposites is dispersing the broad clay sheets in the polymer matrix [175]. This
depends upon the polymer-mediated interactions between the dispersed particles.
The van der Waals interactions between the particles are usually attractive leading
to aggregation∕flocculation of these particles and diminishing the properties of the
nanocomposite. One way of stabilizing the dispersion is to end-graft polymers onto
the particle surfaces. Steric hindrance due to the grafted polymer chains (or polymer
brushes [176, 52, 51]) prevent the surfaces from coming close together, however, their
preferred separation depends upon the effective interaction of the brushes in the free
polymer matrix. In polymer∕clay nanocomposites, depending upon this separation,
the mixture will form an intercalated or exfoliated composite, or a phase separated

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