In the method for preparing a nanocomposite by intercalating a smectite clay with a quaternary ammonium ion, and exfoliating the intercalated clay into a polymer matrix; an improvement is disclosed which augments exfoliation. The smectite clay is edge treated with negatively charged organic molecules prior to the exfoliation. For these purposes a high charge density anionic polymer such as a polyacrylate may be used.