Poly(acrylic acid), poly(vinylsulfonate), and poly(styrene sulfonate) are incorporated between the positively-charged sheets of double hydroxide layers M1-xAlx(OH)2
+ (M = Mg, Ca, Co) and Zn1-xM' x(OH)2
+ (M' = Al, Cr) to form layered nanocomposites. The resulting nanocomposites contain the LDH sheet structures separated by 7.6 – 17.0 Å, which is sufficient to accommodate polymer bilayers between the LDH sheets.
Phase and morphological changes during thermolysis of the nanocomposites with poly(styrenesulfonate) (PSS) are studied by X-ray powder diffraction, scanning and transmission electron micrography, (SEM and TEM) and thermal analyses. Mg4Al2(OH)12CO3·nH2O and the associated PSS / MgAl-LDH nanocomposites show comparable thermal stabilities: the layered structure is lost above 300 °C with the nucleation of MgO and MgAl2O4 phases at approximately 400 and 800 °C, respectively. The PSS / ZnAl-LDH nanocomposite shows complete oxidative pyrolysis of the polyanion at 500 °C, indicating a catalytic effect of zinc oxide on thermolysis. Crystalline oxide products are obtained at approximately 300 °C lower temperature than from thermolysis of Zn6Al2(OH)16CO3·nH2O. SEM and TEM images show that the thermolysis of LDH carbonates produces dense aggregates containing microcrystalline particles, whereas materials obtained from the PSS / MgAl-LDH nanocomposites exhibit a macroporous framework structure.