Intercalative redox polymerization and characterization of poly(4-vinylpyridine)-vermiculite nanocomposite

A new nanocomposite material consisting of poly(4-vinylpyridine) (PVP) and vermiculite is synthesized by the intercalative redox polymerization of VP in the gallery of copper(II) ion-exchanged vermiculite. The formation of a single filament of the polymer in the gallery is confirmed by the increase in gallery spacing of 4.7 Angstrom as indicated by X-ray diffraction (XRD) analysis. Electron spin resonance studies confirm the presence of Cu(Il) upon ion exchange and its absence following redox polymerization. The amount of polymer present in the gallery is found to be similar to 18-19 mass % by thermogravimetric analysis. Confining the polymer to the gallery spacing in vermiculite results in enhanced thermal stability that is evident from the increase in the initial decomposition temperature by similar to 300 degreesC. Differential scanning calorimetry of the nanocomposite indicates that the polymer is confined to a restricted geometry because of the absence of a glass-transition temperature, which confirms the XRD finding. The IR absorption peaks corresponding to PVP and the expected PVP UV pi-pi* transition at 275 nm, along with the XRD and thermal data confirms that the gallery expansion is due to the PVP filament. (C) 2001 John Wiley & Sons, Inc.