Drying of aerogels in different solvents between atmospheric and supercritical pressures

摘要

Crack-free SiO2 aerogels were repeatedly dried with little shrinkage (< 2%) at subcritical conditions by using various solvents as pore liquids. Gels dried in ethanol showed shrinkage below a threshold pressure of 4.7 MPa. When solvents such as iso-butanol, 2-pentanol and iso-octane were used in drying, this threshold pressure was not observed within the pressure range of this investigation. For example, in iso-butanol the gels showed no shrinkage at a drying pressure of 1.8 MPa which is significantly lower than the critical pressure of 4.85 MPa. Subcritical aerogel drying pressure was reduced by using a suitable drying solvent. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 16]