Novel bridged polysilsesquioxane aerogels with great mechanical properties and hydrophobicity

Abstract

Two novel bridged silsesquioxane (BSQ) precursors, 1,4-bis(trimethoxysilylpropylthioethenylphenoxy)benzene and 1,3-bis(trimethoxysilylpropylthioethenyl)benzene, were synthesized from arylacetylenes and 3-mercaptopropyltrimethoxysilane through the thiol-yne click reaction. Then, bridged polysilsesquioxane aerogels were prepared from BSQ precursors alone or together with tetramethoxysilane (TMOS) as a co-precursor through the sol–gel method. The resulted aerogels were characterized by scanning electron microscopy, mercury intrusion porosimetry, thermogravimetric analysis, transient hot-wire method, and water contact angle tests. Their mechanical properties were evaluated by unidirectional compression tests. The properties of the aerogels are strongly affected by precursor content, mass ratio of BSQ to TMOS, and the structures of BSQ. The obtained aerogels do not break even when compressive strain is up to 55% and show high compressive modulus (≥2.46 MPa) and hydrophobicity (water contact angle ≥130°).

Nanoporous Silica–Chitosan Aerogels for Thermal Insulation and Flame Retardancy

“…23 However, the cost of producing conventional SA is prohibitively high due to expensive raw materials and the specialized equipment as well as technologies. For example, the traditional silicon sources for preparing SA are mainly methyl orthosilicate 24 and ethyl orthosilicate, 25 which are not only costly but also possess toxicity concerns. Furthermore, the conventional drying method of SA is supercritical drying, 26 which suffers from drawbacks such as prolonged duration, excessive energy consumption, and poor safety.…”