Double-Network\nMK Resin-Modified Silica Aerogels for\nHigh-Temperature Thermal Insulation

Abstract

Polymer-reinforced\nSiO₂ aerogel materials exhibit excellent\nthermal insulation, flame resistance, and mechanical properties; however,\nthe poor thermal stability of organic components limits their application\nin high-temperature environments. Herein, a double-network MK/SiO₂ aerogel was synthesized by direct copolymerization of a methyl-containing\nsilicone resin (MK) and tetraethoxysilane (TEOS) under the cross-coupling\nof (3-aminopropyl) triethoxysilane (APTES) followed by an atmospheric\ndrying method. The resulting MK/SiO₂ aerogel, presenting\na double-cross-linked MK and SiO₂ network, shows a low\ndensity of 0.18 g/cm³, a high specific surface area of\n716.6 m²/g, and a low thermal conductivity of 0.030 W/(m\nK). Especifically, the compressive strength of the MK/SiO₂ aerogel (up to 3.24 MPa) is an order of magnitude higher than that\nof the pristine SiO₂ aerogel (0.39 MPa) due to the introduction\nof the strong MK network and enhanced neck connections of SiO₂ nanoparticles. Furthermore, the mutually supportive network\nendows the MK/SiO₂ aerogels with significant resistance\nto ablation and oxidation up to 1000 °C, showing a high residual\nrate (89%), a high specific surface area (235.2 m²/g),\nand structural stability after thermal treatment under air atmosphere.\nThese superior mechanical and thermal properties of the MK/SiO₂ aerogels lead to attractive practical applications in energy\ntransportation, thermal insulation, or aviation.