Small angle neutron scattering study of silica gels: influence of pH

The technique of Small Angle Neutron Scattering (SANS) has been used to inv estigate the microstructure, at the nanoscale level, of SiO2 gels at differ ent processing stages. The samples were prepared by the alkoxide route of t he sol-gel process with different pH values. They were measured as xerogels after heat treatment at different temperatures and as wet gels at the gel point and after aging at 60 degrees C. SANS measurements confirmed that pH has a strong influence upon the nanostructure of gels. The present work rep orts the main SANS results obtained in this investigation and their interpr etation. (C) 1999 Elsevier Science B.V. All rights reserved.