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

alpha,omega-Amino acids have been intercalated into alpha-zirconium ph osphate (alpha-ZrP) to give expanded phases enclosing an amino acid mo nolayer. The epsilon-aminocaproic acid-alpha-ZrP hybrid is a particula rly 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 lin ear (e.g., acrylamide) and cyclic (e.g., 2-pyrrolidinone, delta-valero lactam, epsilon-caprolactam) amides as well as macromolecular polyamid es 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 pol ymerization to nylon-6, identified by infrared and C-13 NMR spectrosco pies both in its as-synthesized occluded environment and ex situ follo wing destruction of the phosphate matrix and recuperation of the polym er released. These surface-modified zirconium phosphates are organic-i norganic hybrids and are materials of potential use as protonic conduc tors or as intermediates in the synthesis of novel porous solids.