Polyacrylamide-clay nanocomposite materials prepared by photopolymerization with acrylamide as an intercalating agent

A series of nanocomposite materials consisting of water-soluble polyacrylamide (PAA) and layered montmorillonite (MMT) clay platelets were prepared by the effective dispersion of the inorganic nanolayers of the MMT clay in the organic PAA matrix via in situ ultraviolet-radiation polymerization. The acrylamide monomers functioned as both the intercalating agent and the reacting monomers. As a representative procedure for the preparation of the nanocomposites, organic acrylamide monomers were first intercalated into the interlayer regions of acrylamide-treated organophilic clay hosts, and this was followed by one-step ultraviolet-radiation free-radical polymerization with benzil as a photoinitiator. The as-prepared polyacrylamide-clay nanocomposite (PCN) materials were subsequently characterized by Fourier transform infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. The effects of the material composition on the thermal stability, optical clarity, and gas-barrier properties of pristine PAA and PCN materials, in the forms of fine powders and membranes, were also studied by differential scanning calorimetry, thermogravimetric analysis, ultraviolet-visible transmission spectroscopy, and gas permeability analysis. The molecular weights of PAA extracted from PCN materials and pristine PAA were determined by gel permeation chromatography with tetrahydrofuran as an eluant. (C) 2004 Wiley Periodicals, Inc.