Preparation and Characterization of Ultralow Density Silica Aerogels by Acetonitrile Supercritical Drying

Abstract

This paper deals with the synthesis of ultralow density silica aerogels using tetramethyl orthosilicate (TMOS) as the precursor via sol-gel process followed by supercritical drying using acetonitrile solvent extraction. Ultralow density silica aerogels with 6 mg/cc of density was made for the molar ratio by this method. The microstructure and morphology of the ultralow density silica aerogels was characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. The results show that the ultralow density silica aerogel has the high specific surface area of 812m2/g. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.024 to 0.043W/ (m K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process.

A Special Material or a New State of Matter: A Review and Reconsideration of the Aerogel

“…In addition, to decrease the hydrolysis rate after nucleation is good for obtaining a stable colloid. According to this thought, an ultralight and structurally-fine aerogel was prepared via catalyzing the sol-gel reactions under acidic and alkaline conditions successively, instead of usual one-step acidic catalysis [ 73 , 74 , 75 , 76 ].…”