PDMS was used as an additive to TEOS based gels in order to improve macroscopic properties for applications such as thermal insulators. The morphological features developed in the PDMS/TEOS hybrid materials were studied by small-angle x-ray scattering and small-angle light scattering. The thermal properties of the material are controlled by nanoscale morphology. A main feature in the nano-scale is mass-fractal domains. As PDMS is incorporated into the TEOS system, a macroscopic network structure becomes dominant, and toughness is enhanced. A monolithic structure is observed macroscopically. The results indicate that PDMS can be used to develop micron morphologies for toughening these materials.