Multiphase Assembly of Mesoporous-Macroporous Membranes

The synthesis of inorganic-organic composites and mesoporous materials with structures and functions over different length scales has ramifications in diverse areas, such as large-molecule catalysis, biomolecule separations, miniaturization of electronic devices, chromatographic supports, the formation of semiconductor nanostructures, and the development of medical implants.1-8 The use of organic structure-directing agents to control the structures of inorganic solids has proven successful for designing patterned materials with dimensions ranging from Angstroms to micrometers.9-25 Mesoporous (20-300 Å) materials can be obtained by using long-chain surfactant or amphiphilic block copolymers.10,11,13,15,21,22 Recent reports have demonstrated that stabilized-emulsion5,14,26 or latex-sphere templating15-18,24 can be used to create TiO2, ZrO2, and SiO2 structures with pore sizes ranging from 100 nm to 1 μm. Mann and co-workers20 have coated bacterial threads with silica-surfactant mesophases to combine the macroscopic morphology of the threads with mesoporous length scales. While researchers have concentrated on the organization of patterned inorganic composites with domain separation directed by proteins,20,27-29 lowmolecular-weight surfactants, block copolymer amphiphiles, or preformed polystyrene spheres,15-18,24 little effort has been devoted to creating phase and domain separation20,30 by using concentrated solutions of inorganic salts.