Inter- and intra-primary-particle structure of monolithic carbon aerogels obtained with varying solvents.

Different carbon aerogels were obtained by carbonization of organic aerogels prepared from the polymerization of resorcinol and formaldehyde using potassium carbonate as catalyst. Various solvents were added to the initial mixture to study their effects on the inter- and intra-primary-particle structure of the carbon aerogels. To carry out this study, various techniques were used, including high-resolution transmission and scanning electron microscopy, mercury porosimetry, mechanical tests, N2 and CO2 adsorption at -196 and 0 degrees C, respectively, and immersion calorimetry into benzene. Variation of the solvent used produced changes in the gelation time of the organic aerogels, which gave rise to variations in the inter- and intra-primary-particle structure of the carbon aerogels obtained. The monolith density of the carbon aerogels ranged from 0.37 to 0.87 g/cm3. Samples with a density higher than 0.61 g/cm3 had micropores and mesopores but no macropores. Macro- and mesoporosity had a monomodal pore size distribution. The elastic modulus showed a scaling relationship with density. In all samples studied, which had a mean micropore width of 0.62-1.06 nm, the surface area obtained by enthalpy of immersion into benzene yielded a realistic value of their total surface area.