Abstract: Polymer-clay nanocomposites prepared by reacting a layered material, e.g. a nanoclay, with an onium cation which is sorbed into the adjacent nanoclay layers to form a Nanomer. The Nanomer is subsequently dispersed into a melt-processible polymer matrix to form a nanocomposite. The preferred polymers are nylon MXD6 and its co-polymers. The invention also relates to processes for preparing a nanocomposite and articles produced from a nanocomposite. The polymer-clay nanocomposites improve gas permeability of panels, sheets, film, film laminates and multilayer bottles.