Industrial & Engineering Chemistry Research, Vol.49, No.10, 5001-5005, 2010
General Intercalation of Poly(oxyalkylene)-Amidoacids for Anionic and Cationic Layered Clays
The same poly(oxyalkylene)-amidoacids (POA-amidoacid) were incorporated into two different types of ionic clays, anionic layered-double-hydroxides (Mg-Al LDH), and cationic montmorillonite (MMT). Conventionally, the intercalation is an ionic exchange reaction, i.e. anionic organic salts for LDH and cationic salts for MMT. The successful intercalation using the neutral species of POA-amidoacid implies the existence of a new mechanism for clay intercalation. We prepared the POA-amidoacid from the reaction of maleic anhydride and poly(oxyalkylene) diamine (POA-amine) with different hydrophobic and hydrophilic POA-backbones of 600-4200 molecular weight. The intercalation has resulted in the expansion of the clay basal spacing from 7.8 to 63 angstrom for LDH and from 12.4 to 51 angstrom for MMT, with a high Bragg's regularity of XRD analyses. It appears that the driving force for the intercalation and organic incorporation into the silicate interlayer galleries is dissimilar to the counterion exchange but involving noncovalent bonding between amidoacid functionalities and SiOH species in clay. The intercalation without ionic exchange reaction is effective for generating new clay hybrids with thermal responsiveness in water.