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Preparation of silica aerogel in surfactant-free microemulsion system
  • li liu,
  • hong zhao,
  • ming liu
li liu
JIlin Jianzhu University

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hong zhao
JIlin Jianzhu University
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ming liu
JIlin Jianzhu University
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Abstract

Silica aerogel is a new porous functional material composed of SiO2 particles. In this paper, silica aerogel was prepared by acid-base two-step sol-gel method without solvent replacement and surface modification using water/ethanol/n-hexane surfactant-free microemulsion(SFME) as solvent. The samples were characterized and analyzed by SEM, FT-IR, XRD, BET, TG-DSC, thermal conductivity, and hydrophobic angle. The results showed that when the molar ratio of TEOS, MTES, H2O, EtOH, n-hexane, octyltriethoxysilane, and DEDMS was 0.25: 0.75: 12: 10: 0.1: 0.07: 0.08, the density of silica aerogel in the SFME system was 0.157 g/cm3, the porosity was 93%, the average pore diameter of BJH was 3.92 nm, the average particle size was 15.78 nm, the hydrophobic angle was 152.5°, and the thermal conductivity was 0.0522 W/(m·K). It can maintain good hydrophobicity below 240.5 ℃. Hydrophobicity completely disappears when the temperature exceeds 510 °C.