Double-Network MK Resin-Modified Silica Aerogels for High-Temperature Thermal Insulation

Polymer-reinforced SiO2 aerogel materials exhibit excellent thermal insulation, flame resistance, and mechanical properties; however, the poor thermal stability of organic components limits their application in high-temperature environments. Herein, a double-network MK/SiO2 aerogel was synthesized by direct copolymerization of a methyl-containing silicone resin (MK) and tetraethoxysilane (TEOS) under the cross-coupling of (3-aminopropyl) triethoxysilane (APTES) followed by an atmospheric drying method. The resulting MK/SiO2 aerogel, presenting a double-cross-linked MK and SiO2 network, shows a low density of 0.18 g/cm3, a high specific surface area of 716.6 m2/g, and a low thermal conductivity of 0.030 W/(m K). Especifically, the compressive strength of the MK/SiO2 aerogel (up to 3.24 MPa) is an order of magnitude higher than that of the pristine SiO2 aerogel (0.39 MPa) due to the introduction of the strong MK network and enhanced neck connections of SiO2 nanoparticles. Furthermore, the mutually supportive network endows the MK/SiO2 aerogels with significant resistance to ablation and oxidation up to 1000 °C, showing a high residual rate (89%), a high specific surface area (235.2 m2/g), and structural stability after thermal treatment under air atmosphere. These superior mechanical and thermal properties of the MK/SiO2 aerogels lead to attractive practical applications in energy transportation, thermal insulation, or aviation.