Freeze-dried resorcinol-formaldehyde gels

The texture of resorcinol-formaldehyde gels, previously synthesized by Pekala et al. [1-6], but dried by freeze-drying was studied. The freeze-dried gels present a complex porous structure from nanometer to micrometer length-scale. Taking a standard freezing rate, we study in detail the influence of the molar ratio resorcinol/catalyst on the texture, This molar ratio is one of the parameters under consideration which can lead to a tailoring of the dried gel texture in order to develop adsorbents or catalyst supports of controlled porosity. Characterization methods include nitrogen adsorption-desorption (including the classical and the fractal interpretations), mercury porosimetry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS).