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Polymer-clay nanocomposites exhibit remarkable improvements of the mechanical, thermal, optical, physical and chemical properties compared to the pristine polymers. Formation of polymer-clay nanocomposites, typically exfoliated or intercalated structures, generally involved interactions of the polymers with the silicate nano-plate surfaces of the clays. In this talk, we present preliminary evidence showing dependency of the nanocomposite structure on the interactions with the bulk (lattice) of the plates. Experiments were carried out on the reactions of the natural clay, montmorillonite (approx. 1 weight %) with the aqueous solutions of poly(acrylic acid) at varying temperatures. As the reaction was carried out at 60°C, X-ray diffraction shows the silicate plates were dispersed with fully extended chains of poly(acrylic acid) being intercalated within the interlayer spaces between the plates. X-ray photoemission spectroscopy shows during the intercalation process sodium ions were removed from the silicate surface. In the product from reaction at 85°C or above, the silicate plates were partly exfoliated. The Fe L3,2-edge NEXAFS shows Fe2+ ions within the clay lattice were oxidised by the acidic poly(acrylic acid) solution, which suggests strong reaction of poly(acrylic acid) with the lattice facilitated exfoliation. |