Abstract: Polymer-clay nanocomposites prepared by reacting a layered material, e.g. a nanoclay, with a mixture of two or more onium cations, which are 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 polymer is nylon MXD6. The invention also relates to processes for preparing a nanocomposite and articles produced from a nanocomposite. Polymer-clay nanocomposites improve gas permeability of panels, sheets, film, film laminates and multilayer bottles.