Thermal characterization of poly(styrene sulfonate) layered double hydroxide nanocomposites

Phase and morphological changes during thermolysis of Mg4Al2(OH)(12)CO3 . nH(2)O and Zn6Al2(OH)(16)CO3 . nH(2)O layered double hydroxides (LDH) and their nanocomposites with poly(styrene sulfonate) (PSS) are studied by X-ray powder diffraction (XRD), scanning and transmission electron micrography (SEM and TEM) and thermal analyses. Mg4Al2(OH)(12)CO3 . nH(2)O and Mg2Al(OH)(6)[CH2CH(C6H4SO3)]. 3H(2)O show comparable thermal stabilities: the layered structure is lost above 300 degrees C with the nucleation of the MgO phase at approximately 400 degrees C and the MgAl2O4 phase at approximately 800 degrees C. Zn3Al(OH)(8)[CH2CH(C6H4SO3)]. nH(2)O undergoes complete oxidative pyrolysis of the polyanion by 500 degrees C. Crystalline oxide products are obtained at a temperature approximately 300 degrees C lower than that of thermolysis of Zn6Al2(OH)(16)CO3 . nH(2)O. The SEM and TEM images show that the thermolysis of LDH carbonates produces dense aggregates containing microcrystalline particles, whereas Mg2Al(OH)(6)[CH2CH(C6H4SO3)]. 3H(2)O forms a macroporous solid.