Control of pore morphology in mesoporous silicas synthesized from triblock copolymer templates

In this paper we describe a novel approach for synthesizing calcined mesoporous silicas with tunable pore sizes, wall thicknesses, and pore spacings using mixtures of triblock copolymer surfactants as hexagonal templating agents. Small angle neutron scattering was used to probe the transition from the liquid crystal phase to the calcined mesoporous silicas formed upon condensation and drying. Powder X-ray diffraction, transmission electron microscopy, and nitrogen adsorption techniques were also used to establish pore diameters, silica wall widths, and the hexagonal packing of the pores within the calcined silicas. By use of a direct templating method, the diameters of mesopores and the spacing between the pores could be tuned with angstrom-level precision between the size range of 45-70 and 75-100 Angstrom, respectively. Tailoring of the silica wall widths is also displayed. All the silicas synthesized were highly ordered over distances of at least 2 mum.