Novel Mechanism for Layered Silicate Clay Intercalation by Poly(propylene oxide)‐Segmented Carboxylic Acid

Summary: Poly(propylene oxide)‐amidoacids were used to intercalate montmorillonite clay to afford organoclays with an X‐ray basal spacing as wide as 81 Å. 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 poly(propylene oxide)‐backbones self‐aggregate and consequently widen the interlayer space between neighboring silicate plates.

Postulated structure of the chelation of sodium ions by the poly(propylene oxide)‐amido acid.