Hydrogen bonding in self organized lamellar hybrid silica

X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) investigations have been performed to study the self-assembly properties of lamellar organic-inorganic bridged silsesquioxanes. The organic part consists of an alkylene chain (flexible spacer) between two urea groups. For this study, two samples with different chain length (six and twelve carbon atoms) were synthesized. It is pointed out that the self-assembly properties of the organic component are controlled both by the hydrophobic interactions between alkylene chains and by the hydrogen bonds between urea groups. Infrared results clearly show a direct correlation between the strength of the hydrogen-bond and the crystallinity of the organic-inorganic hybrid materials. Furthermore, the study of the asymmetric stretching CH2 correlated with XRD results indicate that the disorder along the alkylene chain decreases with longer chain length. (C) 2004 Elsevier B.V. All rights reserved.