2-DIMENSIONAL NANOCOMPOSITES - ALTERNATING INORGANIC-ORGANIC POLYMER LAYERS IN ZIRCONIUM-PHOSPHATE

alpha,omega-Amino acids have been intercalated into alpha-zirconium phosphate (alpha-ZrP) to give expanded phases enclosing an amino acid monolayer. The epsilon-aminocaproic acid-alpha-ZrP hybrid is a particularly useful intermediate, since it permits ion-exchange reactions at pH values a low as 2.6 and so provides access to a new area of zirconium phosphate intercalation chemistry. When used as a precursor, both linear (e.g., acrylamide) and cyclic (e.g., 2-pyrrolidinone, delta-valerolactam, epsilon-caprolactam) amides as well as macromolecular polyamides such as protamine, gelatin, and lysozyme can be inserted. Zirconium phosphate platelets are clearly seen in scanning electron microscopy, and there is no evidence for surface sorption of the biopolymers. The epsilon-aminocaproic acid-alpha-ZrP intercalation compound is itself a precursor to a polymer-inorganic nanocomposite since the in situ polymerization to nylon-6, identified by infrared and C-13 NMR spectroscopies both in its as-synthesized occluded environment and ex situ following destruction of the phosphate matrix and recuperation of the polymer released. These surface-modified zirconium phosphates are organic-inorganic hybrids and are materials of potential use as protonic conductors or as intermediates in the synthesis of novel porous solids.