Ref HAL: hal-00163480_v1
PMID 15662678
DOI: 10.1002/chem.200401012
WoS: 000227262000017
Exporter : BibTex | endNote
97 Citations
Résumé:

The synthesis of four bis(trialkoxysilylated) organic molecules capable of self-assembly - (EtO)3Si(CH2)3NHCONH(CH2)nNHCONH(CH2)3Si(OEt)3 (n = 9-12) - associating urea functional groups and alkylidene chains of variable length is described. These compounds behave as organogelators, forming supramolecular assemblies thanks to the intermolecular hydrogen bonding of urea groups. Whereas fluoride ion-catalysed hydrolysis in ethanol in the presence of a stoichiometric amount of water produced amorphous hybrids, acid-catalysed hydrolysis in an excess of water gave rise to the formation of crystalline lamellar hybrid materials through a self-organisation process. The structural features of these nanostructured organic/inorganic hybrids were analysed by several techniques: attenuated Fourier transformed infrared (ATR-FTIR), solid-state NMR spectroscopy (13C and 29Si), scanning and transmission electron microscopy (SEM and TEM) and powder X-ray diffraction (PXRD). The reaction conditions, the hydrophobic properties of the long alkylidene chains and the hydrogen-bonding properties of the urea groups are determining factors in the formation of these self-assembled nanostructured hybrid silicas.