Molecularly ordered inorganic frameworks in layered silicate surfactant mesophases

S. C. Christiansen, D. Zhao, M. T. Janicke, C. C. Landry, G. D. Stucky, B. F. Chmelka

Research output: Contribution to journalArticleResearchpeer-review

110 Citations (Scopus)

Abstract

Self-assembled lamellar silica-surfactant mesophase composites have been prepared with crystal-like ordering in the silica frameworks using a variety of cationic surfactant species under hydrothermal conditions. These materials represent the first mesoscopically ordered composites that have been directly synthesized with structure-directing surfactants yielding highly ordered inorganic frameworks. One-dimensional solid-state 29Si NMR spectra, X-ray diffraction patterns, and infrared spectra show the progression of molecular organization in the self-assembled mesophases from structures with initially amorphous silica networks into sheets with very high degrees of molecular order. The silicate sheets appear to be two-dimensional crystals, whose structures and rates of formation depend strongly on the charge density of the cationic surfactant headgroups. Two-dimensional solid-state heteronuclear and homonuclear NMR measurements show the molecular proximities of the silica framework sites to the structure-directing surfactant molecules and establish local Si-O-Si bonding connectivities in these materials.

Original languageEnglish
Pages (from-to)4519-4529
Number of pages11
JournalJournal of the American Chemical Society
Volume123
Issue number19
DOIs
Publication statusPublished - 14 Oct 2001
Externally publishedYes

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