Organic modification of glass structure. New glasses or new polymers?

The introduction of organic components into glass structures is possible by sol-gel techniques and leads to hybrid materials. The question whether these materials are more likely glasses or organic polymers is discussed. Different data show that the inorganic network structure governs important properties such as brittleness, hardness, or homogeneity. Other properties, such as density, free volume, or thermal stability depend on the organic groupings. Summarizing one can say that organically modified glasses are more like inorganic glasses than organic polymers.