Template Synthesis and Characterization of Layered Al− and Mg−Silsesquioxanes

A series of new layered inorganic−organic nanocomposites, with organic functionalities directly bonded to an inorganic framework via the Si−C bond, were prepared by a template sol−gel synthesis. These layered Al− and Mg−silsesquioxanes were precipitated at room temperature by addition of aqueous base to an alcohol solution containing a mixture of AlCl3 or MgCl2 and a trialkoxysilane with a n-dodecyl, n-octyl, n-pentyl, 3-methacryloxypropyl, isobutyl, or phenyl functionality. The Si/Al and Si/Mg ratios of the reaction mixtures were 2:1 and 4:3, respectively, and were chosen to match the composition of clay mineral pyrophyllite (layered aluminosilicate) and talc (layered magnesiosilicate). X-ray diffraction and electron microscopy show that the products are crystalline with a layered structure. A comparison of basal spacings and length of the organic functionalities is consistent with a ∼10 A inorganic layer and a bilayer arrangement of R groups for Al−silsesquioxanes and an interpenetrating arrangement of ...