The large industrial demand for polymers has lead to an equally large interest in polymer composites to enhance their properties. Clay-polymer nanocomposites are among the most successful nanotechnological materials today. This is because they can simultaneously improve material properties without significant tradeoffs. Recent efforts have focused upon polymer-layered silica nanocomposites and other polymer/clay composites. These materials have improved mechanical properties. These composites have a large reduction in gas and liquid permeability and solvent uptake, enhanced barrier and mechanical properties and are less flammable.