| Abstract
| - The chemical potential difference between homopolymer fractions in block copolymers can be readily usedto selectively design, and cooperatively assemble, inorganic species into highly ordered three-dimensional(3d) periodic composite arrays of separated mesoscale regions. The actual details and symmetry of theseregions and their long-range order can only be determined by 3d imaging and analysis with high-resolutionelectron microscopy (HREM). Of particular interest is the differentiation between configurations with verysimilar organization energies, such as the cubic and hexagonal (SBA-2) closed-packed structures. Mesoporoussilica SBA-12 and functionalized SBA-12 (SH−SBA-12) have been synthesized from the 3-mercaptopropylgroup by using nonionic surfactant C18H37(CH2CH2O)10 (C18EO10, Brij 76) under acidic hydrothermal condition.Relatively large single-phase domains were obtained in SH−SBA-12. The 3d structural solution of SH−SBA-12 was obtained by Fourier analyses of HREM images. The structure is composed of spherical cavities,which are arranged in a cubic close-packed structure, in which each cavity is connected to the twelve nearest-neighbor cavities through openings parallel to the 〈110〉 directions. HREM images of SBA-12 taken overlarge sample regions show that SBA-12 is a mixture of mostly the cubic close-packed phase, which consistof beautifully crystalline narrow bands with the same 3d structure in twin relation to each other and a relativelysmall amount of the 3d hexagonal close packed phase.
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