Template-directed synthesis of periodic macroporous organic and carbon aerogels

We describe a general procedure for the synthesis of ordered macroporous resorcinol-formaldehyde (RF) and carbon aerogels (CA) in which colloidal crystals of polystyrene (PS) spheres were used as templates. With this approach, ordered arrays of PS spheres are infused with a resorcinol-formaldehyde sol-gel solution. Following gelation of the sol, the RF/PS composite was washed with toluene to remove the template. Periodic macroporous RF aerogels were obtained after supercritical drying with liquid carbon dioxide. These materials can then be carbonized under a nitrogen atmosphere to afford the corresponding macroporous CAs. Scanning electron microscopic examination shows that both the organic and carbon materials consist of many hexagonally ordered domains of spherical cavities with different crystal orientations, reflecting the symmetry of the original PS template. (C) 2004 Elsevier B.V. All rights reserved.