The dramatic influence of gelation solvent choice on the structure and mechanical properties of resorcinol-formaldehyde aerogels

Resorcinol-formaldehyde aerogels were synthesised using acid-catalysed polycondensation of resorcinol and formaldehyde in acetonitrile or dimethyl sulfoxide, followed by supercritical drying in CO 2 . The structure and mechanical properties of the aerogels were analysed using low temperature nitrogen adsorption, scanning electron microscopy, small-angle neutron scattering and stress-strain measurements in compression regime. The resorcinol-formaldehyde aerogels possessed a high specific surface area (200–510 m 2 /g) and porosity (41–82%), with a surface fractal dimension of 2.2–2.5. The mechanical strength of the materials reached high values (up to 31 MPa) and was well correlated with the density of aerogels (0.27–0.86 g/cm 3 ). The results obtained demonstrate the dramatic influence of the nature of a solvent used during the gelation of resorcinol-formaldehyde aerogels on their structure and properties.