Poly(propylene oxide)-amidoacids were used to intercalate montmorillonite clay to afford organoclays with an X-ray basal spacing as wide as 81 Angstrom. Differing from the ionic exchange between quaternary ammonium salts and the metal ions in clays, the intercalation mechanism involves a beta-amidoacid chelation with sodium ions in the silicate interlayer confinement. With the end groups tethered on the silicate surface, the hydrophobic polypropylene oxide)backbones self-aggregate and consequently widen the interlayer space between neighboring silicate plates.