Molecular relaxations in hybrid organic-inorganic materials prepared by a sol-gel process

Organic-inorganic hybrid materials based on alkoxysilane-terminated macromonomers synthesised from a hydroxy-terminated hydrogenated polybutadiene, H-PBD, have been investigated. Different morphologies of the hybrid materials are obtained according to the conditions of the synthesis and to the non compatibility between the organic and the inorganic components. In order to establish the relationships between the structure and the properties of the organic-inorganic (O/I) materials, infrared, small-angle X ray scattering, transmission electron microscopy, dynamical mechanical spectroscopy and dielectric measurements have been performed. This paper focuses especially on the analysis of the dielectrical relaxations in a large range of frequencies and temperatures compared with the dynamic mechanical one to propose a model of morphology of the final O/I materials. It is found in particular that a distinct interfacial region between the organic-rich phase and the silicate clusters is developed in the case of the low acid-to-alkoxide ratio for hybrids (based on gamma-amino propyl triethoxysilane) (i.e. for the long periods of gelation). (C) 1997 by John Wiley & Sons, Ltd.