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.