Reactive pore expansion during ammonia vapor post-treatment of ordered mesoporous silica prepared with mixed glucopyranoside and cationic surfactants

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10 Scopus citations


n-Octyl-β-d-glucopyranoside (C8G1) has the potential to serve as a functional, nonionic template for mesoporous oxides, but its use has been limited due to its propensity to form lamellar mesostructures. Here, 2D hexagonal-structured mesoporous silicas with variable pore sizes are synthesized with C8G1 by the "nanocasting" technique (polycondensation of tetramethoxysilane in concentrated acidic solutions with evaporation) by mixing it with cetyltrimethylammonium bromide (CTAB) to promote ordering. In an effort to stabilize the silica network structure, a mild treatment with ammonia vapor at 50 °C is introduced. Without ammonia treatment, the pore diameter remains constant as the C8G1:CTAB weight ratio increases even up to 0.3:1. When the as-made materials are treated with ammonia vapor, the degree of long-range order of the samples increases, and pore expansion is observed which increases in magnitude as the C8G1 content increases. Large degrees of expansion increase pore size fluctuations but do not eliminate long-range order. Materials with well-ordered, uniform pores can be made with C8G1/CTAB mixtures by limiting the amount of ammonia or increasing the amount of silica precursor. A mechanistic study suggests that micelle swelling occurs with CTAB, but is limited by increased polycondensation of silica and favorable headgroup-silica interactions. With the glucopyranoside surfactant, the extent of expansion is greater not only because of a change in the physical interaction with silica, but also because the Maillard reaction occurs under surprisingly mild conditions.

Original languageEnglish
Pages (from-to)65-76
Number of pages12
JournalMicroporous and Mesoporous Materials
Issue number1-3
StatePublished - Feb 1 2008

Bibliographical note

Funding Information:
We gratefully acknowledge financial support from the National Science Foundation (NSF) (Grant Nos. DMR-0210517 and EAR-0521405) and we thank Dr. Bing Tan for help with TEM imaging. We thank Prof. K.W. Anderson for providing access to the optical microscope and Prof. B.L. Knutson for access to the UV–vis spectrophotometer.


  • Expansion
  • Nanocasting
  • Processing
  • Self-assembly
  • Templating

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials


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