The Sol-Gel Method and Its Related Parameters

To discuss hybrid inorganic-organic composite materials, a brief review of sol-gel chemistry is necessary. Since this section focuses on silicate and silsesquiox-ane chemistry, the review of sol-gel chemistry will be limited to detailing some of the nuances associated with silicate alkoxides. After the brief review of sol-gel chemistry, we will present methods for the preparation of hybrid inorganic-organic composite materials, followed by a brief discussion of polyimide-based hybrid composites. 

There are several parameters that can play vital roles in the hydrolysis and condensation reactions (sol-gel process), including the reactivity of the metal alkoxide, the water to alkoxide ratio, the solution pH, the temperature, the nature of the organic ligands, and the nature of the solvent and additive. Another consideration is that 

---