Preparation and synthesis mechanism of highly efficient thermal insulation SiO₂ aerogels

Abstract

Silica (SiO₂) aerogels have excellent physical and thermal properties with high-performance and broad application prospects. In order to obtain SiO₂ aerogels with high thermal insulation performance and explore key process parameters of their preparation, SiO₂ aerogels were prepared via combining sol–gel and freeze-drying processes using tetraethyl orthosilicate (TEOS) as the precursor. Effects of the pH value and the content of deionized water (DIW) on the microstructures and thermal properties of the SiO₂ aerogel were systematically investigated. Results showed that when the pH was 8.0 and the molar ratio of TEOS to DIW was 1:7, the SiO₂ aerogel had the best structure and the lowest thermal conductivity, exhibiting the best thermal insulation effect. In addition, the synthesis mechanism of such sol–gel freeze-dried SiO₂ aerogels was analyzed in depth, and the structural evolution process was also described. This study lays a theoretical foundation for the controllable preparation and process design of SiO₂ aerogels in the future, and has certain guiding significance for promoting their application in the field of efficient thermal insulation.

Graphical abstract

Keywords

silica aerogel / sol–gel / freeze drying / thermal insulation / synthesis mechanism

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