Mechanically robust aerogels derived from an amine-bridged silsesquioxane precursor

Abstract

A novel bridged silsesquioxane (BSQ) monomer was synthesized from 3-(2,3-epoxypropoxy)propyltrimethoxysilane and (3-aminopropyl)trimethoxysilane based on the reaction between epoxy and amine groups. The monomer was used to fabricate aerogels with excellent mechanical properties via sol–gel processes followed by supercritical CO2 drying. The influence of the sol–gel conditions on the chemical structure, morphology and mechanical property of the aerogels was investigated by NMR, TGA, SEM, nitrogen sorption analysis and DMA. BSQ aerogels prepared from the optimal sol–gel procedure showed excellent properties with high mechanical performance (compression modulus of 20.4 MPa) and low density (0.22 g cm−3), which are of great advantage for practical applications. Further, SiO2/BSQ composite aerogels with significantly improved mechanical performance than SiO2 aerogels can be obtained by co-condensing of BSQ monomer and tetraethoxysilane. The abundant hydroxyl groups in the BSQ precursor are believed to contribute to the robustness of BSQ and SiO2/BSQ composite aerogels due to the strengthened skeleton via the intermolecular H-bonds.