Silica aerogels have low dielectric properties owing to their high porosity, however, their application in low dielectrics has been limited because of their low mechanical properties. To enhance their mechanical properties, silica aerogels were modified with low polarizable functional groups with low dielectric constants via covalent bonding in this study. In detail, the covalently bonded low-polarizability groups (i.e., CF₃-phenyl with silica network) were synthesized and characterized by processing them into monoliths and thin films and characterizing their properties. The CF₃-phenyl-functionalized silica aerogels showed an ultralow dielectric constant of 1.52. Meanwhile, Young's modulus of the CF₃-phenyl-functionalized silica aerogels was 30% higher than pristine silica aerogels. Furthermore, the CF₃-phenyl-functionalized silica aerogels were hydrophobic, which is crucial for achieving a low dielectric constant. Our work provides a simple approach for preparing silica aerogels with low dielectric constants, enhanced hydrophobicity, and improved mechanical properties.

DOI: https://doi.org/10.1016/j.ceramint.2022.08.075