Preparation of high-performance SiO₂ aerogel using organic bases as catalysts and surfactants

Hydrophobic SiO₂ aerogels with highly uniform skeletons and excellent mechanical properties were synthesized without any surfactant. Methyltriethoxysilane served as the silicon source, while tetramethylammonium hydroxide (TMAOH) functioned simultaneously as an alkaline catalyst and a solubilizing agent. By simply tuning the TMAOH concentration, the gel network could be precisely engineered. After supercritical drying, the aerogel exhibited a water contact angle of 163.6°, a specific surface area of 704 m² g⁻¹ , and a low thermal conductivity of 19.2 mW (m K)⁻¹ . Its compressive stress reached 0.302 MPa at 50 % strain. Solvent exchange of the wet gel with n-heptane enabled crack-free monoliths to be dried under ambient pressure. For the optimal formulation, the compressive stress further increased to 4.355 MPa at 60 % strain. The straightforward synthesis, superior performance, and the ability to dry the aerogel at ambient pressure without any additional surface modification make this material highly attractive for large-scale thermal-insulation applications. Moreover, exploiting the solubilizing capacity of TMAOH to suppress phase separation during gelation provides a valuable strategy for the preparation of hydrophobic SiO₂ aerogels.