In situ X-ray measurements to probe a new solid-state polycondensation mechanism for the design of supramolecular organo-bridged silsesquioxanes

Abstract

A long-range ordered organic/inorganic material is synthesized from a bissilane, (EtO)3Si-(CH2)3-NHCONH-C 6H4-NHCONH-(CH2)3-Si(OEt) 3. This crosslinked sol-gel solid exhibits a supramolecular organization via intermolecular hydrogen bonding interactions between urea groups (-NHCONH-) and covalent siloxane bonding, ≡Si-O-Si≡. Time-resolved in situ X-ray measurements (coupling small- and wide-angle X-ray scattering techniques) are performed to follow the different steps involved in the synthetic process. A new mechanism based on the crystallization of the hydrolyzed species followed by their poly condensation in solid state is proposed. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.