A novel glycol silicate and its interaction with surfactant for the synthesis of mesoporous silicate

Sattler, Katrin; Hoffmann, H.

doi:10.1007/3-540-48953-3_9

Cited by 33 publications

(14 citation statements)

References 6 publications

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“…The small changes in the value of N measured by TRFQ have been shown to arise essentially from the ethanol formed by the hydrolysis of the TEOS. At this stage we recall that similarly to us Sattler and Hoffmann in a small angle neutron scattering study of the formation of mesoporous silica from Si(OCH 2 CH 2 OH) 4 in the presence of tetradecyltrimethylammonium bromide observed no change of micelle size till the gelation of the system occurred …”

Section: Discussionsupporting

confidence: 52%

Fluorescence Probing Investigation of the Mechanism of Formation of MSU-type Mesoporous Silica Prepared in Fluoride Medium

et al. 2005

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The mechanism of formation of a MSU-type siliceous material from tetraethyl orthosilicate (TEOS) in the presence of the nonionic surfactant tergitol T-15-S-12, sulfuric acid, and sodium fluoride has been investigated using mainly fluorescence probing techniques and, to a lesser extent, dynamic light scattering (DLS) and 29Si NMR spectroscopy. The tergitol micelles present in the systems obtained by progressively generating the reaction mixture giving rise to the mesostructured material by adding to an appropriate tergitol solution sulfuric acid, TEOS, and NaF were characterized by fluorescence probing (micelle aggregation number, micropolarity, and microviscosity) and also by dynamic light scattering (apparent micelle diameter). 29Si NMR experiments were also performed on selected systems after hydrolysis of the TEOS. The fluorescence probing techniques were also used to follow the changes of micelle characteristics with time during the evolution of the full reaction mixture from a limpid solution to a system containing a minor amount of condensed siliceous material. The synthesized solid material was characterized by X-ray diffraction and nitrogen adsorption-desorption analyses. The micelle aggregation number N was found to change only little, and the micropolarity remained constant when going from the tergitol solution to the full reaction mixture. The results of DLS measurements agree with this finding. Besides, while the condensation of silica took place after addition of NaF, the N value increased only very little with time up to the point where a small amount of mesostructured material precipitated out. These results indicate that the interaction between tergitol micelles and the siliceous species formed in the system by the hydrolysis of TEOS and also between micelles and the growing siliceous species must be very weak. As in our previous studies of the mechanism of formation of MCM41-type material from sodium silicate in the presence of cetyltrimethylammonium bromide, it appears that the locus of formation of the mesostructured material is not the micelle surface but the bulk phase. Micelles only act as reservoirs of surfactant providing surfactant monomer that binds to the growing siliceous species.

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Section: Discussionsupporting

confidence: 52%

Fluorescence Probing Investigation of the Mechanism of Formation of MSU-type Mesoporous Silica Prepared in Fluoride Medium

et al. 2005

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“…The increase of the intensity at low q with time indicates the formation of a fractal structure, as observed by other gelation processes . It was shown before that the fractal dimension of a particle can be determined from the slope of the log−log plot. , I ( q ) is of a power-law form I ( q ) ∼ q - D . The exponent D is related to the fractal dimension of the scattering structures.…”

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confidence: 81%

Novel Ringing Silica Gels That Do Not Shrink

2002

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“…First, the precursor is water-soluble and thus allows a direct mixing with the lyotropic liquid-crystal-like phase of the block copolymer in water; second, it does not require a catalyst to start the hydrolysis and condensation reactions. In addition, the ethylene glycol, which is released during the hydrolysis and condensation reactions, is not detrimental for most of the liquid-crystal surfactant mesophases as Hoffmann et al showed in previous studies for an anionic surfactant/silica/ethylene glycol mixture . We extended this work to ethylene oxide-containing block copolymer surfactants since a stronger interaction with the inorganic precursor can be expected due to transalkoholysis reactions and thus a more pronounced influence on the mesostructure is anticipated.…”

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confidence: 88%