Elastic low density aerogels derived from bis[3-(triethoxysilyl)propyl]disulfide, tetramethylorthosilicate and vinyltrimethoxysilane via a two-step process

Abstract

A series of low density, porous structures were prepared using bis[3-(triethoxysilyl)propyl]disulfide (BTSPD), tetramethylorthosilicate (TMOS) and vinyltrimethoxysilane (VTMS) as precursors via a two-step (acid–base) sol-gel process followed by supercritical CO2 extraction. Using statistical experimental design methodology and empirical modelling, the concentrations of BTSPD, TMOS and VTMS were varied in the production of the monoliths and found to have a significant effect on their bulk density, porosity, BET surface areas, hydrophobicity and mechanical properties. Increasing the TMOS concentration significantly increases the surface area and Young's modulus while higher VTMS concentration improves hydrophobicity and higher BTSPD concentration leads to increased elastic recovery after compression. Optimized aerogels produced in the study have a combination of high Young's modulus, good hydrophobicity and near complete recovery after compression in agreement with model predictions.