Novel mechanism for layered silicate clay intercalation by poly(propylene oxide)-segmented carboxylic acid

Abstract

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.