Polymer Nanocomposites: An Overview
In recent years, development of polymer nanocomposites has attracted the interest of a number of researchers, due to their synergistic and hybrid properties derived from several components. Polymer nanocomposites can be defined as a mixture of two or more materials, where matrix is a polymer and the dispersed phase has at least one dimension less than 100 nm . These materials, present either in solution or in bulk, offer unique mechanical, optical and thermal properties. The ideal structure of a nanocomposite involves individual nanoparticles uniformly dispersed in a matrix polymer. The key challenge to obtain the full potential of properties enhancement is the dispersion state of nanoparticles. The thermal and mechanical properties of polymer nanocomposites are strongly related to the morphologies obtained. Based on the degree of separation of the nanoparticles, there are three possible types of nanocomposite morphologies- 1) Conventional composites; 2)
Intercalated nanocomposites; and 3) Exfoliated nanocomposites. When the polymer is unable to intercalate between the silicate layers, a composite of separate phases is obtained, having properties in the same range as that of traditional composites (Figure 1a). In intercalated nanocomposite, a single or sometimes more than one extended polymer chain is intercalated between the silicate layers (Figure 1b). When the silicate layers are completely and homogenously dispersed in a continuous polymer matrix, an exfoliated structure is obtained (Figure 1c) .