Novel route to periodic mesoporous aminosilicas, PMAs

Ammonolysis of periodic mesoporous organosilicas

Teddy Asefa, Michal Kruk, Neil Coombs, Hiltrud Grondey, Mark J. MacLachlan, Mietek Jaroniec, Geoffrey A. Ozin

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

A new route to periodic mesoporous aminosilicas (PMAs) that contain amine functional groups in the framework of a mesoporous network is reported. The materials are prepared via thermal ammonolysis of periodic mesoporous organosilicas (PMOs) under a flow of ammonia gas. PMOs integrate similar or even higher quantities of nitrogen-containing groups upon ammonolysis than similarly treated ordered mesoporous silicas (MCM-41). The quantity of amine groups introduced into the materials was found to depend strongly on the ammonolysis temperature. The largest loading of amine groups was obtained when a well-ordered cubic methylene PMO material without prior vacuum-drying was thermolyzed in ammonia. The ordered mesoporosity of PMOs was preserved during the ammonolysis with only a slight decrease in the mesopore size and the degree of mesostructural ordering. The extent of substitution of framework oxygen by amine and nitride groups was established by solid-state 29Si CP-MAS, 29Si MAS, 15N MAS, and 13C CP-MAS NMR spectroscopies, elemental analysis, and X-ray photoelectron spectroscopy. In some cases, methylene and methyl functional groups were also present in the PMAs along with amine functional groups, as inferred from elemental analysis and gas adsorption, particularly in cases where PMOs were subjected to ammonolysis at 400 and 550°C for several hours. This resulted in new multifunctional mesoporous organoaminosilica nanomaterials with properties that could be tuned by systematically varying the relative amounts of hydrophilic amine and hydrophobic hydrocarbon pendent and framework groups. The stability upon storage was found to be much higher for PMAs obtained from PMOs than for those obtained from MCM-41 silicas under the same conditions.

Original languageEnglish
Pages (from-to)11662-11673
Number of pages12
JournalJournal of the American Chemical Society
Volume125
Issue number38
DOIs
Publication statusPublished - Sep 24 2003

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Amines
Functional groups
Multicarrier modulation
Ammonia
Silicon Dioxide
Gases
Silica
Photoelectron Spectroscopy
Gas adsorption
Mesoporous materials
Nanostructures
Vacuum
Hydrocarbons
Chemical analysis
Nanostructured materials
Nitrides
Nuclear magnetic resonance spectroscopy
Adsorption
Drying
Substitution reactions

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Novel route to periodic mesoporous aminosilicas, PMAs : Ammonolysis of periodic mesoporous organosilicas. / Asefa, Teddy; Kruk, Michal; Coombs, Neil; Grondey, Hiltrud; MacLachlan, Mark J.; Jaroniec, Mietek; Ozin, Geoffrey A.

In: Journal of the American Chemical Society, Vol. 125, No. 38, 24.09.2003, p. 11662-11673.

Research output: Contribution to journalArticle

Asefa, Teddy ; Kruk, Michal ; Coombs, Neil ; Grondey, Hiltrud ; MacLachlan, Mark J. ; Jaroniec, Mietek ; Ozin, Geoffrey A. / Novel route to periodic mesoporous aminosilicas, PMAs : Ammonolysis of periodic mesoporous organosilicas. In: Journal of the American Chemical Society. 2003 ; Vol. 125, No. 38. pp. 11662-11673.
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AU - Grondey, Hiltrud

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