Moisture‐Resistant and Mechanically Strong Polyimide‐Polymethylsilsesquioxane Hybrid Aerogels with Tunable Microstructure

Abstract

Moisture‐resistant and mechanically strong polyimide (PI)‐polymethylsilsesquioxane hybrid aerogels with doubly cross‐linked structures are synthesized through sol–gel technology and supercritical CO2 fluid drying. By using bis(trimethoxysilylpropyl) amine as a cross‐linker, the end‐capped polyamide acid derived from biphenyl‐3,3′,4,4′‐tetracarboxylic dianhydride and 4,4′‐oxydianiline is cross‐linked with a silica network using methyltrimethoxysilane as the silica source precursor. The resultant hybrid aerogels show low density (0.12–0.15 g cm−3), low thermal conductivity (0.032–0.049 W m−1 K−1), high hydrophobicity (125–140°) and good thermal stability (above 435 °C) with tunable microstructure. With the increase of silica sol volume, the microstructure of hybrid aerogels transforms from fibrous network to hierarchical microstructure. Aerogels with high content of silica sol exhibit good moisture resistance, high Young's modulus (Max. 19.6 MPa), and high specific modulus (Max. 131 kN m kg−1), which are attributed to their unique hierarchical microstructure with a sheet skeleton. These hybrid aerogels are promising in the fields of thermal insulation, aerospace applications and so on.

Melamine‐Crosslinked Polyimide Aerogels from Supercritical Ethanol Drying with Improved In‐Use Shape Stability Against Shrinking

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Silver Nanoparticle-Decorated Chitosan Aerogels as Three-Dimensional Porous Surface-Enhanced Raman Scattering Substrates for Ultrasensitive Detection

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Enhancing Mesopore Volume and Thermal Insulation of Silica Aerogel via Ambient Pressure Drying-Assisted Foaming Method

“…The positions and intensities of the absorption peaks of 1 eqv, 0.75 eqv, and 0.5 eqv were essentially the same, indicating that silica aerogels had similar chemical structures. Strong absorption peaks for Si-O-Si were located at 1088 cm −1 and 780 cm −1 [ 26 ]. Stretching vibrations of Si-C bonds were found at 1255 cm −1 , 847 cm −1 , and 759 cm −1 .…”