A procedure to synthesize silica aerogels in a wide range of densities by a single-step base catalyzed recipe

Silicon alkoxides based synthesis of silica aerogels, could be divided into two main approaches; a single-step recipe for a fixed density, benefiting from exceptional reproducibility and simplicity; and a two-step recipe, which enables a wide range of densities, yet includes stages that could hinder reproducibility. A procedure to synthesize aerogels in a wide range of densities is reported. This procedure avoids the sources of variability affiliated with the two-step recipe, and benefits from the reproducibility and simplicity of the single-step recipe. This procedure was formulated as a result of a thorough investigation of varying the molar ratio of the precursors involved in the single-step base catalyzed recipe. Aerogels in densities ranging from 25 to 150 mg/ml were synthesized and analyzed. The analysis indicated that these aerogels have almost identical composition, skeletal structure and pore size distribution. Additionally, a strong correlation between the aerogels' intended and measured densities was achieved.