Abstract

Phase and morphological changes during thermolysis of Mg 4 Al 2 (OH) 12 CO 3 .eta H 2 O and Zn 6 Al 2 (OH) 16 CO 3 .eta H 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. Mg 4 Al 2 (OH) 12 CO 3 .eta H 2 O and Mg 2 Al(OH) 6 [CH 2 CH(C 6 H 4 SO 3 )].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 MgAl 2 O 4 phase at approximately 800 degrees C. Zn 3 Al(OH) 8 [CH 2 CH(C 6 H 4 SO 3 )].eta H 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 Zn 6 Al 2 (OH) 16 CO 3 .eta H 2 O. The SEM and TEM images show that the thermolysis of LDH carbonates produces dense aggregates containing microcrystalline particles, whereas Mg 2 Al(OH) 6 [CH 2 CH(C 6 H 4 SO 3 )].3H 2 O forms a macroporous solid.

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