Preparation of a nanostructured organoceramic and its reversible interlayer expansion

We described previously the liquid phase synthesis and characterization of a nanostructured composite from an aqueous solution containing organic polymer and inorganic ions [J. Mater. Res. 7, 2599 (1992)]. The nanocomposite, termed an organoceramic, consisted of poly(vinyl alcohol) chains intercalated between the principal layers of a hydrated calcium aluminate ceramic, A key structural feature of the organoceramic is the polymer-induced expansion of the interlayer spacing by approximately 10 Angstrom compared to the unmodified ceramic. In this paper, we describe the synthetic scheme that favors organoceramic formation and prove the existence of intercalated polymer by observation of reversible interlayer expansion and contraction in response to changes in ambient humidity. This property is unique to the organoceramic and is not observed in the unmodified calcium aluminate ceramic.