Sol–Gel Synthesis of Solids

Abstract

Abstract The synthesis of glasses and ceramics via the sol–gel route is based on the inorganic polymerization of molecular precursors such as metal alkoxides. Precursor structure and reactivity can be chemically controlled via complexation or acid–base catalysis. Sol–gel chemistry allows the powderless processing of glasses and ceramics, at much lower temperatures than that at usual solid‐state reactions. It provides a convenient and flexible access to nanoparticles, films, and fibers. Moreover, precursors are mixed at the molecular level and multicomponent materials can be formed. Thus, hybrid organic–inorganic materials have been made via the sol–gel route. The organic component can be used as a network modifier during the sol–gel synthesis and then withdrawn, allowing the formation of structured porous materials. It can also remain entrapped in the mineral matrix via weak interactions. Alternatively, organoalkoxysilanes allow covalent binding of organic moieties to silica networks. Such composites fill the gap between polymers and glasses, opening new possibilities for the design of functional materials in the fast developing areas of energy, biotechnology, and medicine.