Conventional polymer composites are widely used in diverse applications, such as construction, transportation, electronics, and consumer products. Composites offer improved properties, including higher strength and stiffness, compared to pristine polymers. The properties of polymer composites are greatly affected by the dimension and microstructure of the dispersed phase. Nanocomposites are a new class of composites that have a dispersed phase with at least one ultrafine dimension, typically a few nanometers [1-3]. Nanocomposites possess special properties not shared by conventional composites, due primarily to large interfacial area per unit volume or weight of the dispersed phase (e.g., 750 m2/g). Clay layers dispersed at the nanoscale in a polymer matrix act as a reinforcing phase to form polymer-clay nanocomposites, an important class of organic-inorganic nanocomposites. These nanocomposites are also referred to as polymer-silicate nanocomposites and organic-inorganic hybrids. Polymer-clay nanocomposites can drastically improve mechanical reinforcement and high-temperature durability, provide enhanced barrier properties, and reduce flammability [4-6]. Clays that have a high aspect ratio of silicate nanolayers are desirable for polymer reinforcement.