Effects of preparation parameters on SiO2 aerogels by single-factor and orthogonal experiments

Abstract

Silica aerogels have attracted increasing attention owing to their unique characteristics such as low density, high porosity and super hydrophobic. Integral and fracture-free SiO2 aerogel monoliths with low density of 0·140 g cm−3 and super-hydrophobic of 153·6° were successfully prepared via one-step solvent exchange and surface modification and ambient pressure drying. The single-factor and orthogonal experiments were conducted so as to investigate the individual and coupling effects of the important preparation parameters on SiO2 aerogels, respectively. Favourable values were first selected by single-factor experiments. Based on the favourable values, the four-factor and three-level orthogonal experiments were conducted aiming at optimisation of the preparation parameters. The optimised parameters were accordingly obtained as 12 hours (hydrolysis period), 1 : 4 (volume ratio of aging fluid), 72 hours (modified period), and 10% (concentration of modifier) for preparing low density and hydrophobic aerogel monoliths.