Computational Modeling And Inelastic Neutron Scattering Contributions To The Study Of Methyl-Silica Xerogels: A Combined Theoretical And Experimental Analysis

In amorphous materials, such as xerogels, the properties are the key to most of their applications. Therefore, it is of great importance to get insight into the xerogel structure. In order to achieve a better understanding of structure formation in methyl-silica xerogels and thus be able to better influence the properties of these materials, we have chosen the molecular approach to model the hybrid-xerogel structure using the density functional theory. A theoretical cage model for hybrid xerogels was performed from the PBEPBE/6-31G(d,p) method. The model could explain the presence of ordered domains in the structure. A comprehensive listing of all IR and Si-29. NMR assignments is provided. The effects in the structure of the organic functional groups incorporated on the host structure network are investigated using inelastic neutron scattering spectroscopy (INS). The combination of experiments and modeling permitted an analysis of the INS studies, including unique INS assignments, contributing to the understanding of the skeletal SiO2 network of silica xerogels and so to obtain information about the structure of this material.