Origin of porosity in resorcinol-formaldehyde aerogels☆

Porod analysis of small-angle X-ray scattering results was used to study the structure of resorcinol-formaldehyde aerogels as a function of monomer and catalyst concentration. Based on an analysis of the shape of the scattering curves, the catalyst dependence of the pore and solid chords and previous work on scattering from precursor solutions, it is concluded that the structure of the aerogels results from nanoscale phase separation in the solution precursor. Remnants of a possible kinetic polymerization process were found at length scales so small that porosity arising from these processes is not penetrated by nitrogen.