Silylation of layered double hydroxides via a calcination-rehydration route.

Silylated layered double hydroxides (LDHs) were synthesized through a surfactant-free method involving an in situ condensation of silane with the surface hydroxyl group of LDHs during its reconstruction in carbonate solution. X-ray diffraction (XRD) patterns showed the silylation reaction occurred on the external surfaces of LDHs layers. The successful silylation was evidenced by (29)Si cross-polarization magic-angle spinning nuclear magnetic resonance ((29)Si CP/MAS NMR) spectroscopy, attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy, and infrared emission spectroscopy (IES). The ribbon shaped crystallites with a "rodlike" aggregation were observed through transmission electron microscopy (TEM) images. The aggregation was explained by the T(2) and T(3) types of linkage between adjacent silane molecules as indicated in the (29)Si NMR spectrum. In addition, the silylated products show high thermal stability by maintained Si related bands even when the temperature was increased to 1000 degrees C as observed in IES spectra.